what are blocks and heads?

haha, as you can see, i'm not very familiar with the inside parts of the engine. i'm sure someone can help me cuz i see these two words thrown around alot!!!

lots of time, i hear ppl say "h22a head with so and so block" or "keep the block and just switch the head". something along those lines; what are blocks and heads? also, if they fit inside a big category, such as, well, i'm not sure, engine parts, something LIKE that, could you please inform me of the other parts under that category. i want a swap, but i want to know every single specific before i even start looking for an engine.

thanks alot for the help!!!

The block (also called the shortblock) is the bottom end of your motor. The engine code is stamped on this. It houses the crank, pistons, connecting rods, cylinder walls, etc. It is pretty much everything bellow the head gasket...all the way down to the oil pan. The head is what is mated to the block. It contains the camshafts, valves, combustion chamber, valve springs, retainers, cam gears. The distributor mounts to it, along with the Intake manifold and the exhaust manifold. The complete motor (minus the transmission) is called the longblock (both the block and the head, intake manifold, exhaust manifold distributor, etc.) hope this ramble helped you a little :)

sorry fishcat,the combustion chambers are in the block,you know where the pistons and rods live.But I'm sure this is just an oversite.