By default, the priority class of a process is NORMAL_PRIORITY_CLASS. Use the CreateProcess function to specify the priority class of a child process when you create it. If the calling process is IDLE_PRIORITY_CLASS or BELOW_NORMAL_PRIORITY_CLASS, the new process will inherit this class. Use the GetPriorityClass function to determine the current priority class of a process and the SetPriorityClass function to change the priority class of a process.