Most servers are Intel based. Not all though.
Most web applications, like this forum, will run on a Winders or a U*ix box. The server operating system is somewhat irrelevant.
Most modern hosting providers like GostMonster or HoDaddy will offer Winders or U*ix platforms. The U*ix one is often cheaper. Unless you have your own "Pizza Box" type server/appliance in your basement. Then the O.S. is up to you, or the person(s) that set up the server.
If the latter, you'll need a static IP, and the internet connection should be reasonably dependable (up time), reasonably secure from the script kiddies, and the server protected from fire/theft/flood/etc.
Then there's the matter of DNS, most all think DNS is voo-doo magic. In a nutshell, DNS converts names (zggtr.org) into numbers (127.128.129.130 which is also called IP4 or dotted quad, unless talking about IP-v6... then it's voo-doo magic
), and numbers are painfully easy to route/direct to the millions of servers around the world... like the server in your basement. You can think of DNS as the Yellow Pages. "Where to I go to find...?"
Rick