Web projects always need CSS and script files. Bundling helps us combine multiple JavaScript and CSS files in to a single entity thus minimizing multiple requests in to a single request.
For example consider the below web request to a page . This page consumes two JavaScript files Javascript1.js and Javascript2.js. So when this is page is requested it makes three request calls:
The below scenario can become worse if we have a lot of JavaScript files resulting in multiple requests, thus decreasing performance. If we can somehow combine all the JS files into a single bundle and request them as a single unit that would result in increased performance (see the next figure which has a single request).