Southern African in origin, its name meaning "humanity towards others", Ubuntu the computer operating system was created by the open-source community with South African firm Canonical, and as their web site says "is free to use and share at home and in business".
It runs on all modern desktops, laptops tablets and netbooks, and has server versions as well. Cloud computing is also one of its strengths.
A worthwhile upgrade from Windows, it rivals Mac OSX for ease of use and reliability. Viruses are almost non-existant in Ubuntu, the most recent one having been rendered harmless years ago. In any case, open-source software is less susceptible by nature although it is still not bullet proof.
So why do I use it?
I do not have to consider licencing issues when I install it. Installation is simple and straightforward, with Ubuntu selecting and auto-detecting its hardware environment and automatically installing the necessary drivers. I do not need expensive additional anti-virus software before I can safely use it. My favourite office and web applications run well on it. Upgrades are simple, with software updates never more than a few clicks away. Extra applications are installed with a few typed words. It's reassuring to know that the code behind it is open-source and checked by thousands and is not veiled in proprietary secrecy.
Only if a must-have application demands another operating system is it worth the hassle and cost of using anything else.