Axum is a popular web framework for building REST APIs in Rust. It is simple to use and has hyper-compatibility with Tower, a library for building network applications. Axum follows the style of REST-style APIs like Express, where you can create handler functions and attach them to Axum's `Router` type. It supports various extractors for handling request data, such as JSON, forms, and headers. Axum also provides support for adding middleware, serving static files, and managing app state. It is recommended to use Shuttle for deployment, as it simplifies the process.