Could someone explain "Gaming Server"?

Ok sorry if this isn't the right place but I have a serious question/issue. I really want to host my own server (don't worry about the internet as I may or may not have a plan but thats the be discussed later) but I'm at a loss to what parts I should be looking at. "Server" parts are sooooo expensive and whats the difference between them and regular computer parts. Please someone explain to me what to do/look for! 

Well, "server parts" are usually more reliable and have features that your typical consumer grade stuff doesn't have.  Things like support for ECC memory and etc.  If you're not going to be doing professional server hosting, consumer grade parts will work just fine.