Q: And what the operating systems are used for. i.e business, domestic, banks, schools and collages to name a few. Like foe example Linux and Apache.
A: This has a huge list of OS's: http://www.dmoz.org/Computers/Software/Operating_Systems/ (go down to the section that starts with AIX). Apache is not an OS - it's an opensource project with a load of sub projects. It's biggest product is the web server, which powers most of the web.