Used Car service questions

[ringstrue]

So we are looking at buying a used car. How does warranty and service usually/should work for this? We are looking at a couple cars that are just a year old or so. Does it make a difference if we buy from the dealer of the same make or not? 

I'm used to getting a new car and having a comfy warranty for atleast the first few years but the used car buying world is totally new to me. Is it typical to not have any warranty?