i'm learning how to setup my own web server at home and would like to know which linux is the best OS for servers. please explain why. any ideas will be greatly appreciated.
I've tried almost every single Linux distribution, and I think the absolute best to start learning with is Ubuntu. It has a great community behind it, so you can ask questions if you need to. More importantly, there is plenty of documentation on the web on how to set up and secure your server. Apt-get it's wonderful for installed software and keeping it up to date. If you're going to be installing it yourself, this process is also easy, and has good documentation behind it as well. If you want some good tutorials on how to set up everything, check out articles.slicehost.com they have tutorials for the three major versions of Ubuntu, as well as other distros. FreeBSD isn't a Linux distribution though. It's a great OS, but isn't very friendly to someone just starting out.
CentOS is the best free OS, Redhat is a paid solution, but is very reliable, and support is excellent.
Been using RH (RHE), Fedora and CeontOS. I could recommend any... Fedora seems to be working very nice, and is easy to use.
You really should test out which distribution is right for you. Each person will have his/her own preference but ultimately you will need to decide which one is "best." An easy way to test out the various distributions is to get a VPS from Linode.com. You can then try for example, CentOS 5, see if you like it and if you don't, you can re-install your VPS with a click of a button with another distribution like Debian, Ubuntu, Slackware, etc.
Debian linux is really good for servers but if you dont mind the extra time, i find that gentoo is the best.