Valves - Intake valve lets in air and fuel mixture. Exhaust valve lets the exhaust gases out. Both valves are compressed during the compression and combustion strokes.
Piston - The cylindrical metal piece that moves up and down within the cylinder. Compresses the mixture, going up. Goes down on combustion.
Piston Rings - Provide a seal around the outside of the piston and the inside of the cylinder. They prevent mixture and exhaust from going into the sump. Keep oil in the sump from being burned or leaked.
Combustion chamber is the volume in which the mixture and gas is created obvioulsy it has a min and max volume. The difference between this is the displacement. So if you have a 4 cylinder engine and each cylinder displaces half a litre then that gives 2.0 litre engine!
Conencting rod connects the crankshaft and piston. The crankshaft turns the up and down motion into revolutionary movement. The faster it goes up and down the more Revs are being produced. Surrounding this crankshaft is the sump which contains oil for lubrication. This oil collects in the oil pan at the bottom.