Webpack is a static module bundler for JavaScript applications that processes source files and transforms them into optimized bundles for browsers. Developed since 2012, Webpack has become the industry-standard build tool for modern web development, offering deep configurability for transforming, bundling, and optimizing application assets including JavaScript, CSS, images, and fonts. Understanding Webpack's core concepts—entry, output, loaders, plugins, and modes—is essential because they form a composable system that lets you control every aspect of your build process, from development speed to production optimization.