In Tiger's Activity Monitor, what is "% Nice" CPU?

I installed OS X Tiger in an emulator, to learn more about how OS X's UI has evolved over the years.

I noticed that Activity Monitor measures the percentage of CPU that is "Nice", in addition to the percentages which come from system processes, which come from user processes, and which are idle.

What does "Nice" CPU usage represent? Are these system processes or user processes, and is there an equivalent in more modern OS X?

Solution 1:

Nice and renice are Unix commands where one can change the priority level of a process.

I used them on workstations many years ago to prioritize my job over other processes.

Will be found on man pages and most Unix books.