When does a Trustee Sale Become a Foreclosure?

[Mike Miller]

When a person defaults on their payments, after a certain period of time if you don't pay it off, the bank just forecloses on you right? But then some people have trustee sales instead? How does that work, the bank gives you the chance to auction it as a trustee sale before foreclosing? 

What brought this up, is a guy I was talking with has been postponing his trustee sale for the past 7 years, living  in the house for free. Everytime it comes up for auction, he manages to postpone it. At what point does the bank say enough is enough, and just foreclose on it? Why would it keep coming up for auction after this long?