Linux is an open-source operating system that was first released in 1991 by Linus Torvalds. It is based on the Unix operating system and is highly customizable, allowing users to modify and adapt the system to suit their specific needs. Linux is known for its stability, security, and performance, making it a popular choice for servers and supercomputers. It also has a large community of developers who contribute to its ongoing development and improvement. Linux is available in many different distributions, each with its own set of features and design.