Aspectual particle "zhe"

It's often been said that the aspectual particle 着 (zhe) functions in Chinese like "-ing" functions in English. Well, yes, both come at the after a verb, but how do you know when to use 着 after a verb, and when to use the basic "在 + Verb" pattern to indicate that an action is in progress? Suddenly the usage of 着 is not so clear-cut.

Usage of aspectual particle 着 can be divided into several main uses.