Final answer:
Free play in context of vehicle brake systems is the pedal movement that occurs before the brake mechanism engages. Correct adjustment is crucial for both safety and efficient operation of the brakes.
Step-by-step explanation:
Free play is the amount of pedal movement before brake application begins. This refers to the slack or loose movement in the brake pedal before the brake mechanism actually starts to engage and slow down the vehicle. Ensuring that the free play is correctly adjusted is important for vehicle safety, as too much free play can result in a delay in braking, while too little free play can cause the brakes to drag.