One of the simplest examples of priority inversion, illustrated in the top diagram in Figure 2, involves three threads: one high (h), one medium (m), and one low (l) priority thread.

The inversion of priorities delays both the low- and the high-priority thread from making progress.

Dependency Inversion Principle states that we should decouple high level modules from low level modules, introducing an abstraction layer between the high level classes and low level classes.