How do touch sensitive electronics work?

Question

For instance, my Bose speakers have a touch sensitive metal surface that mutes the speakers if I touch the center of the volume control. The slightest touch activates it, but If I touch it with anything other than my finger, it does nothing. How does it know that it's my finger??!

Answer 1

Human "capacitance".

Here is a nice article

http://science.howstuffworks.com/question42.htm

Answer 2

Conductivity.