Bundlers like Webpack, Rollup, and Vite are used to process and optimize web assets such as JavaScript, CSS, and images for efficient delivery to browsers. They handle tasks like bundling, code splitting, and transforming modern code into a browser-compatible format.

In practice, I use Vite for most projects — it works out of the box and covers the majority of use cases with minimal configuration. For more specific or lower-level needs, I rely on tools like Rollup or, in some backend scenarios, Webpack, where more control over the build process is required.