Kitchen chemistry: Why do pans stick?

Additional information

Advisory note, in response to feedback from our users:

The chemistry of the adhesion of a protein-based food to a surface is complex. This is due to other factors in addition to the roughness of the surface. Please beware of introducing misconceptions when teaching this topic. The article given here addresses only some of the reasons why foods do not stick to Teflon (PTFE), and explanations given on why PTFE adheres to the metal in the pan should not be confused with the science behind why protein-based foods stick to pans. These two processes are distinct.