Introduction to React

What is React?

React is a JavaScript library used to build user interfaces (UI). It helps developers create websites and web applications easily by dividing the UI into small reusable components.

React is mainly used for:

Creating single-page applications
Building fast and interactive websites
Managing dynamic content efficiently

Example:
Instead of reloading the entire webpage, React updates only the part that changes. This makes websites faster and smoother.

Who Created React?

React was created by Jordan Walke, a software engineer at Meta

React was first used inside Facebook in 2011 and later released to the public in 2013 as an open-source library.

Why Was React Created?

Before React, building large and dynamic websites was difficult because updating the user interface repeatedly made applications slow and hard to manage.

React was created to solve these problems:

Improve website performance
Make code reusable using components
Simplify UI development
Handle dynamic data efficiently

React introduced the concept of the Virtual DOM, which updates only necessary parts of the webpage instead of reloading the whole page.

This made web applications faster and easier to maintain.

What is the Difference Between a Library and a Framework?

Library	Framework
A library provides specific functions for developers.	A framework provides a complete structure for building applications.
Developers control the flow of the program.	The framework controls the flow of the program.
Used for solving particular tasks.	Used for building full applications.
Example: React	Example: Angular

Simple Understanding
Library = You are in control.
Framework = The framework is in control.

React is called a library because it mainly focuses on building user interfaces.

What is a Framework?

A framework is a collection of tools, rules, and libraries that provides a complete structure for developing applications.

Frameworks help developers:

Organize code properly
Reduce development time
Follow standard practices
Build complete applications faster

Examples of frameworks:

Angular
Django
Spring Boot

What is a Build Tool in React?
A build tool helps developers create, run, and optimize React applications.

Build tools perform tasks such as:

Converting modern JavaScript code into browser-compatible code
Bundling files together
Improving performance
Starting development servers

Popular React build tools:

Vite
Webpack
Create React App
Example

When developers write React code:

const element = <h1>Hello</h1>;

Browsers cannot understand JSX directly.

The build tool converts it into normal JavaScript that browsers can understand.