Help sims question! 10 points.?

Ok so i bought sims 3 a long time ago and couldn't play it because they are saying i need to have internet connection. So i bought sims 2 yesterday. So do i need to register sims 2 online aswell. And can you please explain this whole registration thing to me. For example if i do the registration somewhere else rather than my computer can i play sims 2 on my computer offline. And after registration do i to have any more internet connection before starting the game offline everytime? Please help :(