On MW2 how do kill rewards count in a game?

Answer 1

If you kill someone and continue without dieing then, it is a kill streak.

In certain kills you have you kill streak which may be set up from 3 to 25.

Most kill streaks counts towards your killstreak, such as pred missile, harriers, pavelows, chopper gunner, etc.

But some don't. When they are from carepackeges, or emergency airdrops, and sentry guns doesn't.

The more kills you get in a row, you are awarded with better kill streaks.