gambits

this is a dumb question, but what's a gambit?

It depends who you ask, most people will say its when one player offers material in exchange for some kind of compensation. 

A gambit is a chess opening in which the first player risks or sacrifices material, usually a pawn, with the hope of achieving a resulting advantageous position

There are NO dumb questions, especially in chess- we all are learning, even the Masters

This definition is from Wlikepedia

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For example a player might sacrifice a pawn or two so they can develop more pieces

And one of the most famous gambits, if not the most, is none other than...

the King's Gambit!

1.e4 e5 2.f4!

Everyone was playing this gambit along with the Evans gambit in the 19th century, yet the KG is older. Nowadays it is very rarely used by the strongest GM's, but it remains a good weapon in the hands of many club players. There are a lot of variations and defenses, most of them giving very sharp play, so if you happen to like complications and chaos on the board, the King's gambit is definitely for you.

The Evans Gambit:

1.e4 e5 2.Nf3 Nc6 3.Bc4 Bc5 4.b4!

Other famous gambit that isn't exactly a gambit is the Queens gambit:

1.d4 d5 2.c4

black can take the pawn but white can get it back if he wishes,  with a good position.

Well I would say there are gambit openings, and then there is general gambit play. A gambit is sacrificing a piece in a situation where you do not immediately forsee regaining the piece. I say that to distinguish it from combinations involving sacrifices where the player has forseen the forced continuation. That is sometimes why some people will say the queens gambit is not a "real" gambit since the pawn offered is almost assured to be given back. For beginners though, in many openings you'll see a gambit like the famous King's Gambit 1.e4 e5 2. f4. Here white offers a pawn and hopes that since that important e5 pawn of black will be removed, the attacking chances are worth the pawn. Gambit play is exciting! Try it out sometime. Also remember that not all gambits occur in the opening moves. Sometimes in the middle or endgame a player decides to offer a piece hoping it will end in a win for them. Good luck.

A player attempts to sacrifice a pawn(or sometimes two) and if it is accepted, that player gains positional, attacking, or otherwise(but not material) compensation.