Notes: Hidden by the crankset in this picture is the bottom bracket. There are actually two bottom brackets. You call the bearing assembly that the crankset spins on the bottom bracket. And you also call the part of the frame that the mechanical bottom bracket is screwed or pressed into the bottom bracket. Often the serial number of the bicycle is stamped into the bottom of the frame bottom bracket. Other common bicycle serial number locations include the left rear dropout and on the bottom of the frame seat tube above the bottom bracket.
