What is Linux?
Linux is a mostly free operating system that works with many CPUs, motherboards and computers, including older models. There are many different versions of Linux, some of which are proprietary, such as Red Hat Enterprise Linux, but most of the versions are free and open source, which means you can download them and install them yourself for free and even use them for your own business without paying anyone (unless you need a consultant to help you install and set them up). Open source means that it is supported largely by volunteers who like computers and programming. Anyone can suggest an improvement or change to the basic Linux operating system, but the change must usually get the approval of a core number of enthusiasts who act like a "board of directors" of that particular version of Linux. The great thing about all the Linux versions or "distros" (distributions) is that there are thousands of programs and games that work with them; many of these software packages are very similar to name-brand programs (some are even compatible with the commercial versions of same).
Although the Linux operating system is free, there is a much steeper learning curve to getting it installed and functioning correctly. If you like a challenge and know a little bit about how computers work from the Windows or the Mac operating systems, then it shouldn't be too difficult to learn Linux. There are many helpful forums, user groups, YouTube videos and websites that can assist you with any problems or questions.
Linux is based on the old UNIX operating system, which is still around. (UNIX was the basis for the NeXT computer, which Steve Jobs developed in the '90s.) Linux was created by Linus Torvalds, a famous Finnish-American computer programmer, in the '90s, but is still being updated and improved today by Torvalds and millions of other enthusiasts around the world.
It is very easy to mess up your Linux installation and then have to reinstall it, especially if you are a beginner to Linux, so be sure to back up your data frequently. Or don't use it for anything important until you have some facility with it and have a stable Linux system. It can be very satisfying when you figure out a problem or learn a new trick or tip in Linux.
Here are some of the more popular Linux distros:
Red Hat Enterprise Linux
Linux is generally more secure than the other operating systems, but nothing is perfect, of course, so you still have to take precautions. Some Windows and Mac OS viruses that your Linux system encounters will not infect your Linux computer, but can accidentally be transferred to Windows and Mac machines by e-mail or other transfer methods. There are free or low cost antivirus/antispyware programs that you can download and install that will protect your Linux installation and the Windows/Mac machines of your contacts.