Differences between Ray Tracing, Path Tracing, and Photon Mapping?

Hello everybody. Can anyone tell me the pros and cons of Ray Tracing vs Path Tracing vs Photon Mapping? And maybe an example of a rendering engine for each type… thanks!

The Pixar site has a lot of information on those topics.
http://renderman.pixar.com/view/fundamentals

They are all essentially methods of tracing rays. Path tracing is just a specific type of ray tracing, and photon mapping is a form of ray tracing where rays are fired from lamps, and then color and illumination data is stored in a data structure that gets interpolated and looked up to estimate secondary lighting at render time. This requires a preprocessing step unlike ray and path tracing.