fs2 is a purely functional, type-safe, and composable I/O library for Scala. Built on Cats Effect, it provides a rich set of abstractions for handling asynchronous and concurrent operations, making it easier to build scalable and robust applications. Its features include streaming, sockets, files, and process handling, all within a functional paradigm. fs2 empowers developers to reason clearly about side effects and construct complex I/O pipelines with confidence.