The capacitive touch sensor has an initial low state. When touch the output of the sensor changes from low to high. The sensor has a high sensitivity and can pick up touch even through paper or cloth.
After powering up the sensor has a 0.5 seconds stabilization time after which it can be used.
The sensor has a LED that switches on when touch is detected by the sensor.
The sensor has a voltage range from 3.3-5V and can be used directly with 3.3V and 5V controller boards.
A short introductory video can be found here