If you buy a computer game you can install it on your computer and your best friends computer so that you can play together

Not exactly, if you install it on ur friend's too, you can't play at the same time because you HAVE to have the disc while playing. If you can figure out a way of using it without the disc it's illegal. if i don't have computer i can installit in my friendsand we will both playor if he likes that i can give it to my friendor i invite him to play to my home