I'm looking for some kind of info on why guitarists even use cabinets & pre-amps.

I'm a noobie, so I'm trying to gain as much info as possible on why cabinets &/or half-stacks are even necessary. I know that I'll eventually need this equipment, but I don't want to walk in a store completely CLUELESS, you know.

Any links, opinions, advice are greatly welcome!!
Head and cab is for people who want a certain cab with their head (the cab contains the speakers). Head and cab also makes it possible to buy new amps but save money on the speakers.

You'd buy a combo if you don't care about the above.
You are probably in the wrong forum and I guess one of the mods will move you.

Very simply a head is slang for a guitar amplifier which sits on a speaker cabinet. The amplifier takes the tiny electrical signal from the guitar and turns it into electrical energy or watts. The speakers inside the speaker cab turn the electricity into sound. A combo is an amplifier and the speakers all built into a single box, which makes it simple to carry and set up but means you are stuck with the manufacturers choice of speakers.

You need a combo with your current level of knowledge.

Have fun
thanks for the replies, but I'm not asking for anyone to suggest what I need to buy. I'm just looking for some information (or website) about the details of cabinets/half-stacks/pre-amps etc...

I'm not looking for suggestions on what I "need", but thanks.