● React JS Components are the building blocks of any React application. They are reusable pieces of code that can be combined to create complex user interfaces and applications, making development faster and more efficient. 
● Components allow developers to split UI elements into separate parts, each with its own logic, state, and markup – making creating UIs a lot easier than when using plain JavaScript. 
● Additionally, components also support powerful features such as props (which let you pass data from one component to another), lifecycle methods (which define how an element should behave at different stages of its life cycle), and state management (for better control over data). 
● Components provide developers with a lot of flexibility in terms of customizing the look and feel of their user interface while still maintaining consistency across all elements or applications they use. 
● With the help of components, it is much easier for teams to work together on projects since they can reuse existing code while working on individual pieces at the same time. Furthermore, because most modern frameworks, such as Angular JS, have adopted this pattern, it has become even simpler for developers who already know them well to transition into React quickly! All these factors make components an invaluable tool when crafting amazing experiences with React JS! 
There are two types of components in React: functional components and class components. 
Functional components are simple JavaScript functions that return JSX. Here is an example of a functional component that renders a heading: 

import React from 'react'; 
function FirstHeading() { 
return <h1>Hello, React!</h1>; 
} 
export default FirstHeading; 

Here, the component is a simple function that returns JSX 
Class components, on the other hand, are JavaScript classes that extend React. Component class. Here is an example of a class component that renders a heading: 

import React, { Component } from 'react'; 
class FirstHeading extends Component { 
render() { 
return <h1>Hello, React!</h1>; 
} 
} 
export default FirstHeading; 

The main difference between functional and class components is that class components have access to additional features such as lifecycle methods and states. Components can also receive data from their parent component via props. Props are similar to function arguments and are used to pass data from the parent component to the child component. Here is an example of a component that receives a name prop and renders it in a heading: 

import React from 'react'; 
function FirstHeading({ name }) { 
return <h1>Hello, {name}!</h1>; 
} 
export default FirstHeading; 

Here, the ‘name’ prop is passed to the component as an argument and is used to render dynamic content.