What's a Sub 2? How would I offer one to a seller?

I’m a newbie to the real estate investing world and see a lot of talk on these forums about Sub 2. What exactly is a Sub 2? How would I offer one to a seller? Under what circumstances does it make sense to offer one to a seller rather than a lease/option or a land contract?

I sincerely appreciate advice and guidance!

IF a person is in preforeclouser is a good time

You are basicly taking on there debt /mortgage

But it is staying in there name

So you better make sure you can make there payments or have a way to get them made

Or you could get in to big trouble in some states