Linux is an operating system in the same way that Microsoft Windows is an operating system. In fact, Linux is an alternative to Microsoft Windows.
An operating system is the software (computer program) that makes your computer work. It operates your computer hardware (keyboard, mouse, monitor, drives etc), and operates your computer software (word processor, games, music). Without an operating system, a computer is just an expensive door stopper.
So, Linux is an alternative to operating systems like Microsoft Windows and Mac OS, except:
Linux doesn't belong to anyone, so there are many different versions of it designed for lots of different sorts of people. If you have never tried Linux you will want to start with a distribution that is easy to use.
Imagine a kid in a candy store - and all the lollies are free. The mouth waters. The mind boggles. So many options. So many taste combinations. Where do a start? How long can I stay?
Now imagine a geek in his electronic equivalent. A free operating system. Tens and hundreds of thousands of free programs. All freely available from the internet. All customisable. And you can share them all freely with your friends. What is the ideal combination of programs he can put together? What is the coolest look? What will his friends think?
Or imagine a company trying to put together the most effective and stable collection of applications they can - either for themselves, or to share with other companies. Out of all of the available programs, only so many will fit on the CD they are sharing. What are the best programs to choose?
This is what a Linux distribution (distro) is: A customised version of Linux combined with a set of free programs put together by an individual, a community, or a company.
Different distros may also have different "flavours", different installation methods, differerent ways of updating software, and different interfaces. Some are designed for specific groups of people to help with specific jobs (e.g. recording studios, scientists, playing back movies and multimedia), while other distros are more general.
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