The Anatomy of a Bicycle

Head Tube:
Top Tube: Sloped downwards toward the seat tube, connected between the seat tube and the head tube
Down Tube: Connects the heat tube to the bottom bracket shell
Seat Tube: Contains the seat post
Seat Stay: Connects the Seat tube to the rear fork dropouts
Chain Stay: connects bottom bracket to rear fork
Bottom Bracket Shell:

Handlebars: The handlebars are used by the rider to steer the bicycle.
Stem: Connects handlebars to the head tube
Fork: Holds the front wheel, steerer is attached to the fork and connects it to the handlebars allowing the rider to steer
Integrated Shifter/Brake Lever: Uses hydraulic fluid to transmit the force from your hand to the brake
Cable Housing: Holds the cables in place and give it something to push against.
Brake Cable: How the hydraulic fluid gets to the brakes
Brake: Reduces the speed of the bicycle.

Integrated Shifter/Brake Lever: Mechanism to control the gear ratio
Front Derailleur: Mechanism that shifts the chain on the bike when the gear is changed
Crank Arm: Uses the rotational motion produced by the pedals to drive the chain.
Chain Rings: Part of the crankset, attached to the crank arm.
Chain: Utilizes the power provided by the crank arm to drive the wheels of the bicycle.
Rear Derailleur: Mechanism that shifts the chain on the bike when the gear is changed
Cassette: the set of rear sprockets that attaches the hub on the rear wheel

Spokes: Connecting rods between the bicycle hub and rim to transfer loads caused by the weight of the rider and the bike.
Rim: Outer edge of the wheel holding the tire
Tire: Locked into the rim allows the bike to grip the surface it is riding on, ride smooth
Rear Dropout: Where the axle of the rear wheel is attached, allows the rear wheel to be removed without derailing the chain
Fork Dropout: Where the axle of the front wheel is attached.