Understanding the Purpose of React Router

React Router is a critical library in the React ecosystem. It primarily serves the purpose of handling navigation and routing within a React application. With its dynamic and user-friendly nature, React Router enhances user experience by providing seamless navigation across various components of an application.

When a user navigates across different sections or pages of a React application, React Router keeps the UI in sync with the URL. For instance, consider a blog application where users can navigate between a list of blog posts and the detailed view of a selected post. The React Router would manage the URLs for the different post views, thereby providing a unique URL for each post that can be bookmarked, shared, or used to directly access the post later.

React Router utilizes the concept of components to define routes. It allows developers to nest routes, thus creating complex user interfaces with deeply nested views. In addition to this basic functionality, React Router also provides several other features like redirecting, switch, and the ability to inject route specific data into the components being rendered.

Here is an example of React Router in action:

import { BrowserRouter as Router, Route, Link } from 'react-router-dom';

function App() {
  return (
    <Router>
      <div>
        <nav>
          <ul>
            <li>
              <Link to="/">Home</Link>
            </li>
            <li>
              <Link to="/about">About</Link>
            </li>
          </ul>
        </nav>

        <Route path="/" exact component={Home} />
        <Route path="/about" component={About} />
      </div>
    </Router>
  );
}

In the code snippet above, Router is the router component, Route maps a path to a component, and Link is used to navigate through the application. There are two routes defined – Home and About, each pointing to a different component. When users click the links, they are taken to the relevant view without the page refreshing, hence providing a smooth user experience.

Best practices while working with React Router include making use of the exact parameter in the Route component to prevent unexpected matches and the Switch component to render only the first Route or Redirect that matches the location.

React Router is not used for managing global state, conditional rendering, or connecting to external APIs. Although these are crucial aspects of a Reactive application, they fall outside the realm of React Router's purpose. Understanding and correctly implementing React Router's functionalities contributes to creating feature-rich, user-friendly React applications.