Linux was once considered only a "hobbyist" operating system. Originally created in the last half of 1991 by Linus Torvalds while a student at the University of Helsinki in Finland. Linus was looking to make a Unix-like operating system that he could run on an Intel based system, for his own personal use:

      From: torvalds@klaava.Helsinki.FI (Linus Benedict Torvalds)
      Newsgroups: comp.os.minix
      Subject: What would you like to see most in minix?
      Summary: small poll for my new operating system
      Message-ID: <1991Aug25.205708.9541@klaava.Helsinki.FI>
      Date: 25 Aug 91 20:57:08 GMT
      Organization: University of Helsinki

      Hello everybody out there using minix -
      I'm doing a (free) operating system (just a hobby, won't be big and
      professional like gnu) for 386(486) AT clones. This has been brewing
      since april, and is starting to get ready. I'd like any feedback on
      things people like/dislike in minix, as my OS resembles it somewhat
      (same physical layout of the file-system (due to practical reasons)
      among other things).
      ...
      

Linux and/or Open Source software is often referred to as "free" software. It is true that you can download and install Linux for no cost, but "free" in this case refers more to "free" as in open for inspection, modification, copying and compiling. Linux is not owned by anybody or any one company. These basic conditions lead to software code to be exposed to extreme scrutiny by other programers. Software bugs will be fixed, functionality added and reliability tops other operating systems. In addition, the work is completed in a much quicker time frame.