A brake pedal that feels soft and travels close to the floor most likely indicates

Correct answer to question 24 (Auto & Shop Information): air trapped in the hydraulic lines

Method

Brake fluid does not compress but air does, so a bubble in the line absorbs pedal travel and gives a spongy feel. That is why the system is bled after any repair that opens it. A warped disc gives pulsation instead, and worn pads give noise.