this depends on the car but ill lay it all out. you have the master cylinder filled with dot 3 brake fluid. you have a brake booster which helps with braking, brake lines, brake hose connected to the caliper, brake calliper, piston/s in the calliper, brake pads, bleeder nipple, rotor. some cars have drum brakes which have a wheel cylinder, the drum, brake shoes, springs which connect everything like the e brake, self adjuster etc, the brake adjuster wheel, bleeder nipple, a piece of metal which is used to apply the e brake, a brake cable which applies the parking/e brake. some cars may have an abs module or braking computer which prevent the wheels from locking up under hard or frantic braking which causes skidding. thats pretty much it simplified
