Linux is an open-source, Unix-like operating system that runs on multiple hardware platforms. There are over 350 Linux distributions available including popular options like Ubuntu, Fedora, Debian, and Red Hat. Linux distributions are suitable for different users, with Ubuntu being good for all levels of users. Linux offers advantages like low cost, reliability, security, and built-in applications, but also has drawbacks like sometimes being not user-friendly and having limited hardware support and applications for computer gamers. Linux is widely used in servers, supercomputers, desktops, laptops, and many other devices.