these quistions can sound pretty stupid to some of you ,just keep in mine i have never done this or tried to do this

ok i have been thinkin of having my own server at my house and i have been thing and i have come up with these quistions please help

1.Do they sell computers specificly for being a server,if so do they take up alot of power(electricity)

2. Do i have to have it on all the time (i kinda know the answer to this one but just making sure)

3. can i use a old computer for a server

4 If there are any things i need to know please let me know