will some one give me an in depth definition of wat a cab or cabinet is and wat it does
A cab is basically speakers mounted into a rolling chasis or frame. A cab is meant to be attached to a head, which is the part you plug your guitar into. Cabs come in different size and can be determined by looking at the ratio.

I.E. a 4 x 12 cab? is Four 12in Speakers in a cab, 2 x 10 is two 10in speakers, etc.

It's bascially just speakers in a box, really.
How many guitar players does it take to change a light bulb?

Twelve. One to change the bulb and eleven to say they could do it better.

A cabinet connects to a head. They combine forces to create disturbances in the air. A head without a cab cannot make any noise. Thus, the cabinet acts as an partner in crime for the head to create the sound coming from the head.

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Don't ever run your head without being plugged into a cab or you will fry amp
Marshall Vintage Modern 2466 and Gibson Les Paul Custom is litteraly sex in my ear!!!

"THESE AMPS GO TO 11!!!!!!!!!!"

seriously dude?

cab, it has your speakers in it + everything already said (watch your impedances).
alright thx everyone who answered. this might be a dumb question, but its serious. wat is the head?, is that like the part that has all the dials on it like treble bass and middle?...i have a little 15 watt practice amp so it probably doesnt have a cab does it?
A combo amp, is technically a head and cab smooshed into one. The head has all the controls for tailoring your sound and your cab has the speakers that make the sound.