Final answer:
Linux is an open-source operating system developed by Linus Torvalds as a response to the expensive UNIX systems. It gained popularity due to its free distribution, configurability, and effectiveness across multiple hardware platforms.
Step-by-step explanation:
Linux emerged as a groundbreaking open-source operating system when Finnish graduate student Linus Torvalds expressed dissatisfaction with the high costs of UNIX, leading to the development of a kernel called Linux in 1991. This new system offered free distribution, easy configurability, and the ability to run on a variety of hardware, which appealed to hackers and eventually caught the attention of PC manufacturers like IBM and Dell. These companies began to offer Linux as an alternative to Microsoft's OS to reduce system costs and break the monopoly, while organizations like NASA discovered the power of networking PCs running Linux for high-performance computing.
The history of computing saw major players like IBM, Microsoft, Sun Microsystems, and SGI control the operating system market through proprietary versions of UNIX, which diverged from its open origins. Linux's introduction countered this model by providing a platform that was not only free but also highly adaptable to different requirements. Eventually, Linux's flexibility led to its pervasive use in various domains from embedded systems to the most powerful supercomputers in the world.