Understanding React Router and Its Primary Use

React Router is primarily used for routing and navigation in React applications. Unlike traditional websites where web pages are pre-rendered and served to the user, applications created with React are Single Page Applications (SPA). This means only a single web-page is sent to the client and new content is loaded dynamically through the JavaScript, improving the user experience by making the web app faster and more responsive.

React Router is a standard library for routing in React. It allows developers to sync components with the URL. This means different components can be shown to the users based on the paths in the URL.

For instance, consider a website with home, about, and contact pages. Without a router, you would have to write complex logic to show and hide different components based on user actions or certain conditions. However, with React Router, you can simply assign different paths for different components, and React Router manages the rest.

Here is a basic example:

import React from 'react';
import { BrowserRouter as Router, Route, Switch } from 'react-router-dom';
import Home from './Home';
import About from './About';
import Contact from './Contact';

const App = () => (
  <Router>
    <Switch>
      <Route exact path="/" component={Home} />
      <Route path="/about" component={About} />
      <Route path="/contact" component={Contact} />
    </Switch>
  </Router>
);

In this example, the Home component will render when the URL path is "/", About will render for "/about", and Contact will render for "/contact".

It's essential to follow best practices when using React Router to maintain readability and efficiency in your codebase. Some of them include:

• Use <Switch> to render only the first Route or Redirect that matches the location.
• Use <Route path> to determine the path of the URL that the route matches.
• Use <Route exact> when you want to prevent further route matching.

Thus, while libraries like Redux can be used to manage state, and performance optimization can be achieved in various different ways, routing and navigation is accomplished using the React Router library. With this in mind, the React Router library is a vital part of any React developer's toolkit.