Master Modern AI Engineering with Production Code

Accessibility on the Platform

Web development

Codecademy is committed to providing a high-quality learning experience for all learners. That includes accommodating different usage forms such as auditory, motor, or visual restrictions, limited hardware, or other acce...

Affordances, Signifiers, and Clickability

Web development

For users on the web, the mouse click is perhaps the most fundamental human-computer interaction. The webbecamethe web partially through the power ofhypertext, or text in one document that links to other documents or res...

Authentication and OAuth

Web development

Authenticationis the process used by applications to determine and confirm identities of users. It ensures that the correct content is shown to users. More importantly, it ensures that incorrect content is secured and u...

Authentication vs Authorization vs Encryption

Web development

Authentication, authorization, and encryption are all key concepts in web security, but it’s easy to confuse them. In this article, you’ll learn what these concepts are, and what roles they play in web security.

Bootstrap: Creating Menus, Navbars, and Modals

Web development

In the first Bootstrap article, we worked on the codebrainery web page, starting with a basic template for the project. If you don’t already have it, you candownload codebrainery herebefore we dig into Bootstrap further...

Browser Compatibility

Web development

Web developers will often have a preferred Internet browser. Naturally, that same browser is the one used to preview websites and web applications in development. There are, however,a multitude of browsers(and many versi...

Building Projects with VS Code

Web development

As you move through various lessons and paths here on Codecademy, you may find yourself needing to create a project on your own computer and not on the Codecademy learning environment. This can be tricky, but it’s an exc...

Building a Redux Store from Scratch Using Vanilla JavaScript

Web development

Though thereduxpackage provides thecreateStore()method for us, examining how this powerful object can be created using vanillaJavaScriptwill help illuminate how Redux works under the hood. This article is for learners wh...

Change Log

Web development

We’ve made changes to some of our SQL content, which will go live on September 30, 2026. These updates focus on freshening up datasets so that content feels more relevant to current-day examples. As a result of these upd...

Characteristics of a good Test

Web development

A test suite is a collection of tests that you can run against a piece of software. The goal is for these tests to catch any errors in your software before you make it available to the end user.

Comparison of Build Tools

Web development

The internet’s growing landscape of available build tools raises many questions: How do different build tools compare with one another? What important features differentiate one build tool from another? What are the idea...

Connecting Page Elements to a Dataset

Web development

Acollection,dataset, and page elements are necessary components for transmitting data between the database and pages on your site. A collection is where your data is held inside of Wix’s built-in database. A dataset lin...

Consider Design While You Build

Web development

Whatever you are setting out to build will be used by real people—a minimum of one (you) and a maximum of billions around the world! When you write the first few lines of code you should have an answer to the question -...

Create Stunning Tailwind CSS Forms: A Step-by-Step Guide

Web development

Have you ever wondered how websites make their forms look cool and easy to use?

Create Your First Local HTML/CSS Project

Web development

In this article, we’ll cover how to take the CSS skills you’ve learned on Codecademy and use them to create a basic web page built entirely from the tools you have on your computer. Before you proceed, you should already...

Create a URL Using Slugs

Web development

Picture this. You’re scrolling through the internet, find a cookie recipe, and click on the “Share” button to send this link to your friend:https://downshiftology.com/recipes/gluten-free-chocolate-chip-cookies/

Create and View a Web Page on Your Computer

Web development

When you navigate to a web page on the Internet, the browser is doing a lot of work. The browser reads all the necessary files (HTML, CSS, andJavaScript) and interprets those raw resources to paint the complex page you s...

Creating Dynamic Pages

Web development

Collections are tools to help you store information that you would want to use on your website. You’ve seen that you can use collections to create a dataset that directly interacts with page elements.

Creating a React App

Web development

React is a powerfulJavaScriptlibrary developed by Meta (formerly Facebook) for building dynamic user interfaces. Its component-based architecture and efficient rendering have fueled widespread adoption among developers,...

Data Structure APIs

Web development

Data structures are all about choosing the right tool for the job. Do you need to store data in an ordered way, or do you just need to be able to store it and retrieve it quickly? What’s more important to your use case:...

Database Scaling Strategies

Web development

When thinking about a software system’s scalability, we must consider the performance of one of the most common system resources: adatabase. Databases play a crucial role in the overall performance of any system that is...

Dataset Basics

Web development

Data is stored in a database, located in the back-end of a website (an inaccessible component that visitors don’t interact with). Database usage can range in complexity, from something as simple as storing a user’s profi...

Debugging in Visual Studio

Web development

In this video, you’ll learn how to debug your ASP.NET applications using Visual Studio’s debugging tools. If you don’t already have Visual Studio, followthis set-up article.

Deploy Rails to Heroku

Web development

After developing aRailsapp locally, the next step is to put it online. After developing a Rails app and previewing it locally on your computer, the next step is to put it online so others can see it. This is called deplo...

Deploying a Back-End with Heroku

Web development

Note: This article is currently teaching deployment usingHerokuwhich no longer offers a free tier plan.

Deploying a Flask App

Web development

Note: This article is currently teaching deployment usingHeroku.Heroku has announcedthat they are deprecating their free offering on November 28th, 2022. We are aware of this issue and are working hard on creating conten...

Deploying a Full-Stack App with Heroku

Web development

Note: This article is currently teaching deployment usingHerokuwhich no longer offers a free tier plan.

Deploying a Simple Python Script With Flask

Web development

In this article, we will cover how to locally deploy aPythonapplication using Flask, including:

Deploying a Static Site with Netlify

Web development

If you want to share a site that doesn’t have a backend and provides the same information to all visitors, then deploying a static site would be perfect. As you know, the most efficient way to deploy these static sites i...

Deploying to GitHub Pages

Web development

GitHubis a great tool to store projects and to collaborate with others, but its usefulness does not stop there. We’ll use a service called GitHub Pages to share our web page creations on the World Wide Web.

Depth-First Search: Conceptual

Web development

Depth-First Search is an algorithm used for searching tree data structures for a particular node, or node with a particular value associated with it. Depth-First Search is also more generally used as a tree traversal alg...

Design - Color

Web development

Color is an important tool in a visual designer’s toolbox. The color of an everyday object communicates a lot to an observer. For example, why is every stop sign red? It’s the same with web pages; users learn a lot about...

Express.js Explained: What it is and How to Use it in Your JavaScript Project

Web development

Express.jsis a fast, unopinionated, and minimalist webframeworkforNode.js. It simplifies the process of building server-side applications and APIs by providing a robust set of features for handlingHTTP requests, routing,...

From Editor to Output

Web development

How does a program work? From our perspective, we write some code, run it, and then something (usually) appears in the output terminal; however, that isn’t the full story. In this article, we’re going to break down all o...

Getting Started with Heroku

Web development

Note: This article is currently teaching deployment usingHerokuwhich no longer offers a free tier plan.

Getting Started with Netlify

Web development

Put simply, Netlify is an all-in-one platform that makes it incredibly easy to deploy static web applications to the world in record time.

Getting Started with Visual Studio Code

Web development

In this article, we will go over the steps necessary to download a popular text editor called Visual Studio Code, also referred to as “VS Code.” By the end of this article, you will be all set up to start interacting wit...

Getting Started with Visual Studio Code and Building HTML Websites

Web development

In this article, we will go over the steps necessary to download a popular text editor called Visual Studio Code, also referred to as “VS Code.” By the end of the article you will be able to create a folder in Visual Stu...

Getting Started with the Wix Editor

Web development

Now that you have a Wix account, you probably got started with one of Wix’s website templates. The next step is to add your own personalized touch! This can mean creating additional elements like images or videos to your...

Getting User Input in Node.js

Web development

Node.jsallows you to runJavaScriptcode outside of a browser window, offering powerful tools to interact with a computer filesystem, run web servers, and create terminal applications. Node handles these tasks by runningas...

Getting started with Node Package Manager

Web development

Note: This article assumes that you have some experience withNode.js and Node.js modules.

Git Setup for Mac and Windows Computers

Web development

In this tutorial, we walk through the process for using Git locally on your personal computer, and usingGitHubto back it up. We walk through creating your personal GitHub account, setting up Git on your computer, startin...

Going Beyond with Heroku

Web development

Note: This article is currently teaching deployment usingHerokuwhich no longer offers a free tier plan.

Going Beyond with Netlify

Web development

This article presumes knowledge of Netlify and continuous deployment. Follow the steps in“Getting Started with Netlify”and“Deploying a Static Site with Netlify”to prepare for this article or get a refresher.

HTML Class vs ID: What’s the Difference and When to Use Each

Web development

Theidattributein HTML assigns a unique identifier to a single HTML element. This identifier can be used to style the element withCSS, interact with it viaJavaScript, or create internal links within a webpage. Sinceidvalu...

HTML5 Game Development with Phaser

Web development

The internet is for many things, but it has nearly always been for games. And while the days of iconic Flash games likeLine RiderandThe Helicopter Gameare behind us, a new world of HTML5 games has taken hold. Leading the...

HTTP Errors: 404

Web development

There are five types of HTTP status codes that report on communications between the client and server. The 400-level codes denote aclient-sideerror, meaning an error that originated from an action taken by the user of aw...

HTTP Requests

Web development

This page is generated by a web of HTML, CSS, andJavascript, sent to you by Codecademy via the internet. The internet is made up of a bunch of resources hosted on different servers. The term “resource” corresponds to any...

HTTP Requests in Velo

Web development

Previously, we covered howgetJSON()can be used to “ask” for information from another website through a GET request. The GET request works by calling a URL endpoint, which is the specified location from where we can retri...

Handy Git Operations

Web development

Git provides us with a vast number of different commands that are listed on thedocumentationwhich can be intimidating at first. We will break down a couple that are powerful for daily tasks.

How To Create a Free AWS Account

Web development

In this tutorial, we will explain how to create anAWSFree Tier account. The sign-up process involves the following:

How Users Scan: Learning from Eye Tracking Research

Web development

You designed a beautiful web page. The color schemes and typography are perfect, the assets are beautiful, and the call-to-actions are intuitively positioned. Given all these things, you can count on users to interact wi...

How to Build Web Apps Using Vite

Web development

In this article, we will useViteto bundle an existingweb app. Vite may be the right build tool for you if your project contains many modules as it can bundle files at lightning speed bypre-bundling dependencies.

How to Build a Website on GitHub Pages: Complete Step-by-Step Guide

Web development

GitHub Pages, a tool provided byGitHub, lets you easily create and deploy a website online. GitHub allows you to store all the files and code for your website in a repository. You can then use GitHub Pages to generate a...

How to Create a Website

Web development

When building a website, whether professionally or as a hobby, there are some easy steps to make sure that you start correctly. You will need a text editor installed on your computer. If you don’t have one, clickhereto r...

How to Take This Course

Web development

'The Codecademy Team, composed of experienced educators and tech experts, is dedicated to making tech skills accessible to all. We empower learners worldwide with expert-reviewed content that develops and enhances the te...

How to Use Chrome Web Developer Tools: Complete DevTools Guide

Web development

Modern websites require powerful debugging tools, and Chrome’s built-in web developer tools (also called developer toolbar or DevTools) provide everything you need. Here’s how to access Chrome developer tools instantly:

How to use Jupyter Notebooks: A Complete Tutorial

Web development

Jupyter Notebooksare a powerful way to write and iterate on your Python code for data analysis. Rather than writing and re-writing an entire program, Jupyter Notebooks allow you to write code in separate blocks (or “cell...

Installing Django

Web development

Django is a high-level web framework written inPython, used to quickly develop complex database-heavy websites like Instagram, Robinhood, and Youtube.

Installing and Using PostgreSQL Locally

Web development

In this article, we will be exploring the extremely prevalent database engine called PostgreSQL (or Postgres, for short). We will describe what it does, its main uses, and then explain how to set it up and use it on your...

Introduction to CDNs

Web development

Otto, an Idaho small business owner, maintains an e-commerce website selling used bikes. They host their website on aserverin their hometown of Boise, Idaho. Their business has recently attracted the attention of a lot o...

Introduction to Data Wrangling and Tidying

Web development

Frequently when we work with data, we encounter unstructured and/ormessy data. Messy data can take a variety of forms. This could mean any of the following:

Introduction to Load Balancing

Web development

When dealing with the scalability of our software systems, we may often come across the challenge of dealing with an influx of requests. For example, imagine running a popularweb appthat sells dog apparel. We just releas...

Introduction to NoSQL

Web development

In the world of databases, there are many different ways to organize and store data. At this point, we are familiar with the concept of relational databases that store data in rows, form relationships between the tables...

Introduction to Testing with Mocha and Chai

Web development

This article provides a high-level overview of tests using the Mocha and Chai frameworks.

Java Program Structure

Web development

Java programs have a specific structure in how the code is written. There are key elements that all Java programs share.

JavaScript Glossary

Web development

Update: Cheat Sheets BETA is here!

Javascript Guide: Arrays

Web development

Arrays areJavaScript’s ordered lists that can store any data types including Strings, Numbers, and Booleans.

Learning from Solution Code

Web development

When you compare your solution to the official solution code, you’ll likely find that there are more differences than you were expecting. This is to be expected, and doesnotmean that your solution is wrong!

MVC Architecture Explained: Model, View, Controller

Web development

MVCarchitecture is a fundamental design pattern that helps developers organize code by separating an application into three interconnected components. If you’re wondering what is MVC, it stands for Model, View, Controlle...

Mocking In Tests

Web development

Mockingis the process of creating a fake version of an external service for testing purposes, particularly in unit tests and integration tests. Mocking is effective in testing individual units of code without relying on...

MongoDB Aggregation Pipelines: A Hands-on Tutorial

Web development

Analyzing data and extracting metrics requires several tasks such as filtering, sorting, grouping, etc. In MongoDB, we can perform these operations using aggregation pipelines.

MongoDB Aggregation Stages Explained

Web development

While analyzing data, we often need to filter, sort, and aggregate it to calculate metrics like sum, count, and average for different values in the dataset. For example, let’s say we want information about the average sa...

MongoDB Data

Web development

By now, we know that MongoDB is a NoSQL document database and that databases like these have some distinct differences relative to relational databases. In this article, we will dive deeper into the technical aspects of...

MongoDB Data Modeling Basics

Web development

When working with databases, we typically are given a blank slate with regards to what data we want to store. However, one of our most important decisions is not just the data we store but also how the data will be organ...

Outside-In Test-Driven Development

Web development

When software engineers and development teams build new features, they’re faced with challenging questions along the way. Some include:

Push to GitHub

Web development

When developing an app, here’s a common approach:

React: The Virtual DOM

Web development

DOM manipulation is the heart of the modern, interactive web. Unfortunately, it is also a lot slower than mostJavaScriptoperations.

Reading Tests with Mocha and Chai

Web development

This article is a practical guide to reading tests written with the Mocha and Chai frameworks. In order to write code to pass test cases (often called ‘specs’), you need to familiarize yourself with how to read tests!

Rebrandly URL Shortener API

Web development

In this article, we will go over how to register a Rebrandly account and obtain an API Key for theRebrandly URL Shortener API. Afterward, we’ll use this information to successfully navigate throughJavaScript: Requests!

Red, Green, Refactor

Web development

Test-driven development(TDD) is an approach to software development where you write tests first, then use those tests to drive the design and development of your software application.

Represent Everyday Things with Objects

Web development

When we take a look at an item, we can come up with a few key characteristics that describe it. Take for instance, a dog. When we think of a dog, we might describe it using characteristics like its name, its body size, f...

Request-Response Cycle I

Web development

When developing a Rails app, therequest/response cycleis a useful guide to see how all the app’s files and folders fit together. The request/response cycle traces how a user’s request flows through the app. Understanding...

Request-Response Cycle II

Web development

When developing aRailsapp, therequest/response cycleis a useful guide to see how all the app’s files and folders fit together. The request/response cycle traces how a user’s request flows through the app. Understanding t...

Request-Response Cycle III

Web development

When developing aRailsapp, therequest/response cycleis a useful guide to trace how a user’s request flows through the app. A common category of web apps that are built with Ruby on Rails are form-based apps. These kinds...

Ridesharing Algorithms: Optimization and Iteration

Web development

As the world becomes more technological, algorithms are increasingly making appearances in our lives. Whether it’s the app that you use to order a pizza or the custom playlist that you listen to each week, there are more...

Run a Full-Stack Web Application

Web development

In this article, you will learn how to use npm and MongoDB on your computer to run the Cake Bar application that you interacted with in theWhy Test?course. You will also run the Cake Bar test suite from your terminal and...

Running JavaScript in the Browser Console

Web development

Along with HTML and CSS,JavaScript(JS) makes up one of the core languages inweb development. JS code is normally added using the HTML<script>element for executing in web browsers, but most modern browsers also provide a...

Running Tests and Interpreting Output with Mocha and Chai

Web development

To run tests for your projects, first open the root project directory in your terminal. If you haven’t already, runnpm installto install all necessary testing dependencies. Finally, runnpm testin your terminal. This co...

Set Up with Git and GitHub

Web development

In this tutorial, we walk through the process for using Git locally on your personal computer and usingGitHubto back it up. Specifically, we’ll walk through creating your personal GitHub account, setting up Git on your c...

Setting Up Node

Web development

This video will show you how to download and install Node.

Setting Up Postman

Web development

Postman is a GUI that aids in the development of APIs by making it easy to test requests and their responses in an organized way. Everything you can do in Postman you can also do through the command line, but Postman mak...

Setting Up a Backend

Web development

In contrast with a website’s frontend, where visitors see and interact with the page, thebackendis the part of the website that visitors have no direct interaction with. The backend is where data, like account informatio...

Setting Up and Using Screen Readers

Web development

Creating a good user experience requires us to think carefully about the diverse needs and devices of our users. We as designers and developers know that not everyone sees, hears, or reads content in the same way.

Setting up a Wix Account

Web development

The Wix Editor contains hundreds of stunning, customizable elements that you can use to create your site. Choose from images, text, shapes, strips and more to make your site interesting and beautiful!

Spies with Sinon

Web development

In testing, aspyis a function that observes and records information about another function’s calls including arguments, return value, thethisvalue, and exceptions thrown (if any). The information that is observed by the...

Spinning Up A Local Server

Web development

Before you begin, make sure that you have the following tools installed on your computer:

Standard Controller Actions

Web development

Ruby on Railsdefines seven standard controller actions can be used to do common things such as display and modify data.

Test-Driven Development

Web development

Web developers have different workflows for creating and maintaining projects. For example, when implementing responsive design, some developers will program “mobile-first” by starting with the mobile view and scaling up...

Testing Types

Web development

At different stages of production for a particular project, you may encounter the opportunity for different types of tests, which can vary in scale and resource intensity, as well as serve different purposes. The types o...

The Testing Pyramid

Web development

Full-stack web applications are often large and complex, and can grow to serve hundreds of different views to millions of users. As the size of a codebase and number of users grow, the cost of bugs compounds — from losin...

The tsconfig.json File

Web development

TypeScript features are extremely useful: for one, it allows us to add types to regularJavaScriptcode. It also checks for syntax errors even before run time. It even provides tooltips that show you why some code might th...

Transforming Code Errors into Learning Opportunities

Web development

When you get started with coding, it’s inevitable that bugs will show up in your code. You’ll get unintended behaviors, and you even get a long, possibly scary looking, error alongside your bug(s). Even when you’re a sea...

Typography Design

Web development

Typography is the art of arranging text on a page to make it legible and appealing. Decisions about the arrangement of text are just as vital to site design as color, layout, and image selection. Text has the power to gr...

Up Next on Velo

Web development

In the beginning, you used Wix to drag and drop elements, but since then, you’ve done so much more. From creating simple Wix websites to comfortably using the platform to build dynamic websites in Velo, you’ve become a p...

Users Don’t Read Web Pages

Web development

You designed a beautiful web page. The color schemes and typography are perfect, the assets are beautiful, and the call-to-actions are intuitively positioned. Given all these things, you can count on users to interact wi...

Web Development Change Log

Web development

Dear Learners, we have added a new module covering Interfaces to ourLearn Gocourse. Due to this additional content, you may see a drop in your progress.

Web Programming on a Chromebook

Web development

If you haven’t set up your local Linux environment on your Chromebook yet, please read theProgramming Locally on a Chromebookarticle first.

Web Security: Not An Add-On

Web development

As we become increasingly connected through the Internet by access through the computer, our phones, and even household devices, security has become a hot topic. Attacks can happen from any corner.

Web UI Conventions

Web development

Websites and the ways that people expect to use them have evolved together over the years. Features or layouts that were difficult to use were discarded, and features that worked well became more and more common, further...

What Is AWS?

Web development

In this article, we will learn the following:

What Is JSON?

Web development

In a world inundated with data, it is becoming more important to know how to work with a variety of data. As programmers, we need to be able to transfer our populated data structures from any language we choose to a for...

What is ASP.NET Razor Pages?

Web development

According to Microsoft, the makers of the software, ASP.NET is: “anopen sourceweb framework…for building modern web apps and services with.NET.”

What is Back-End Architecture?

Web development

Software engineers seem to always be discussing the front-end and the back-end of their apps. But what exactly does this mean?

What is CSS-in-JS

Web development

This article will explore CSS-in-JS as a concept and evaluate the pros and cons of using CSS-in-JS. This article will not prescribe any specific library or syntax for using CSS-in-JS, as examples of both will be provided...

What is Digital Accessibility?

Web development

Accessibility refers to designing devices, products, and environments such that individuals with disabilities or sensory impairments can successfully use the device or product.

What is HTTP? Understanding HTTP Requests

Web development

HTTP (Hypertext Transfer Protocol) is used to structure requests and responses over the internet. HTTP requires data to be transferred from one point to another over the network. The transfer of resources happens using T...

What is Product Usability?

Web development

Can you remember a time when a product you used left you with a miserable experience? Perhaps a particular tool was difficult to use, or a website made it difficult for you to perform a simple task (like logging in, for...

What is Programming?

Web development

Programming is, quite literally, all around us. From the take-out we order, to the movies we stream, code enables everyday actions in our lives. Tech companies are no longer recognizable as just software companies — inst...

What is REST?

Web development

REST, orREpresentationalStateTransfer, is an architectural style for providing standards between computer systems on the web, making it easier for systems to communicate with each other. REST-compliant systems, often cal...

What is SQLite?

Web development

In this article, we will be exploring the extremely prevalent database engine calledSQLite. We will describe what it does, its main uses, and then explain how to set it up and use it on your own computer.

What is Spring Boot?

Web development

In aprevious article, we learned how components of a Spring application are configured as Spring beans and injected as dependencies into other components by the Inversion of Control (IoC) container. For example, one comp...

What is Wireframing?

Web development

Before we build something, it’s a good idea to make a plan for what we’re going to build. For example, if we’re building a house, we shouldn’t do it without planning with designs and blueprints. When developers make plan...

What is a Database Index?

Web development

Indexesare a powerful tool used in the background of a database to speed up querying. Indexes power queries by providing a method to quickly lookup the requested data.

What is a Relational Database (RDBMS)?

Web development

SQL and relational databases work together to store and manage structured data efficiently. A relational database organizes information in tables with rows and columns, while SQL (Structured Query Language) provides the...

What is a Single Page Application (SPA)?

Web development

Wikipedia definesasingle-page application (SPA)as “a web application that interacts with the web browser by dynamically rewriting the current web page with new data from a web server, instead of the default method of the...

What is a Web Application? Complete Guide to Web Apps

Web development

A web application is an application software that does not require installation and can instead be accessed from a remote server via web browser. Web applications are made for interaction, allowing users to send and cons...

What is the $w Selector

Web development

By now you should be familiar with the Wix Editor and its Code Panel feature which allows you to write and apply code to your website. When you open the Code Panel, you’ll see default boilerplate code in all the files of...

Why Learn Asynchronous JavaScript?

Web development

Before we can get intoasynchronous JavaScript, we need to first talk about whatasynchronouseven means.

Why Object-Oriented Programming?

Web development

So far, you’ve built two kinds of C++ programs:

Wireframe to Wire-fame

Web development

In this project, you will fire upAndroid Studio, create a brand new project, and design the layout needed to make Unquote a reality. You will use Android Studio and the Layout Editor to create a layout that will serve as...

Wix .fetch

Web development

Information is continuously changing - things like hit song charts, the stock market, and the weather are in constant flux. For any information to be relevant, it has to stay up-to-date. Now, imagine if you had a site th...

Wix Built-in Methods and Functions

Web development

In this article, you’ll dive deeper into working with previously encountered Wix elements. Using Wix’s built-in methods, you can write code to change components of a Wix website and create an engaging, interactive websit...

Wix Lightbox

Web development

TheWix lightboxis aweb designelement, sometimes referred to as a “modal pop-up” or “modal window” that responds to user actions. It consists of a window for content like a message, image, or form, and an overlay, which i...

Working in the Code Panel

Web development

Wix is a powerful website builder that gives you all the tools to create your own customized website either from scratch or using a template.