WSL, or Windows Subsystem for Linux, is a compatibility layer that allows users to run a Linux environment directly on Windows without the need for a virtual machine or dual-boot setup. It enables developers to use Linux command-line tools and applications alongside their Windows applications, making it easier to work in a mixed environment. Introduced by Microsoft, WSL supports various Linux distributions, such as Ubuntu, Debian, and Fedora. This feature is particularly beneficial for software developers, system administrators, and anyone who prefers Linux tools while using a Windows operating system.