The priority level for a thread is a scheduling weighting that is applied within the priority class of its owning process.

The thread priority levels are:

• Idle
• Lowest
• Below Normal
• Normal
• Above Normal
• Highest
• Time Critical

The combination of process priority class and thread priority, defines a range of scheduling priorities with some overlap. The lowest thread priority in a priority class gives the same scheduling priority as the highest thread priority in the priority class that is one lower.

See the Win32 Programmers Reference for a more detailed discussion of thread priorities.