Here's how BundleConfig works:Bundle Registration: In the BundleConfig class, you define bundles by combining multiple CSS or JavaScript files into logical groups. These bundles can represent common sets of files used across your application, such as libraries (e.g., jQuery, Bootstrap) or custom scripts and styles.Minification and Optimization: Along with combining files, you can also specify whether to enable minification and/or optimization for the bundled files. Minification removes unnecessary characters (such as whitespace and comments) from the files to reduce their size, while optimization applies additional optimizations, such as combining and reordering script references.Bundle Rendering in Views: Once bundles are defined in BundleConfig, you can reference them in your views using the @Scripts.Render() and @Styles.Render() helper methods. These methods generate HTML markup to include the bundled files in your page.Conditional Bundling: Bundles can be conditionally enabled or disabled based on whether the application is running in debug or release mode. In debug mode, bundles may be disabled to allow easier debugging of individual files, while in release mode, bundles are typically enabled for improved performance.Here's an example of how BundleConfig might be configured:// App_Start\BundleConfig.csusing System.Web.Optimization;public class BundleConfig {public static void RegisterBundles(BundleCollection bundles){// Define bundlesbundles.Add(new ScriptBundle("~/bundles/jquery").Include("~/Scripts/jquery-{version}.js"));bundles.Add(new ScriptBundle("~/bundles/bootstrap").Include("~/Scripts/bootstrap.js","~/Scripts/respond.js"));bundles.Add(new StyleBundle("~/Content/css").Include("~/Content/bootstrap.css","~/Content/site.css"));// Enable minification and optimizationBundleTable.EnableOptimizations = true;} }

it is used to register the bundles by the bundling and minification system. Many bundles are added by default including jQuery libraries like - jquery.validate, Modernizr, and default CSS references.