I have about a million n00b questions that I need answered...i'll start with these

[CoreyRS]

What entails a top end?
What entails a bottom end?
Why do I care about my oil pressure?

[nofearhawk]

Top End - Cylinder head
Bottom End - Shortblock
Combined = longblock
Low oil pressure, parts of the engine don't get enough oil, friction, heat, kaboom

[Pothole]

^word

[itsmatt33]

Top End - Cylinder head
Bottom End - Shortblock
Combined = longblock
Low oil pressure, parts of the engine don't get enough oil, friction, heat, kaboom

just about sums it up

[MikeWire]

Top End - Cylinder head
Bottom End - Shortblock
Combined = longblock
Low oil pressure, parts of the engine don't get enough oil, friction, heat, kaboom

Good, explanation. To expand on that and get more detailed on the individual parts, the top end/cylinder head includes: head body, valves, valve guides, springs, retainers, cam shafts, cam followers (lifters), cam chain, chain tensioner, cam gear, valve cover, head gasket, and various gaskets.

Bottom end includes: Block, crank, crank/main bearings, main caps & bolts, connecting (con) rods, con rod bearings, con rod pin/retainer, pistons, piston rings, oil pump and various gaskets, freeze plugs and seals.