Jamming?

I have heard this term a few times recently but i am not sure what it means. could someone explain it

Jamming is when several players limp in the pot while you are at the big blind. Because of all these limpers you can assume none of them have very strong hands, therefore none of them can call an all-in and that is what the "jammer" does. To summarize-it is pushing all-in while on the big blind with players who have limped behind you.