[IPython-user] What is System time in timing report?

[Dick Moores]

In [12]: run -t -N100 1s.py

IPython CPU timings (estimated):
Total runs performed: 100
   Times :      Total       Per run
   User  : 4.08950523041 s, 0.0408950523041 s.
   System:        0.0 s,        0.0 s.

What is "System"? And what kind of things in a script would raise 
System time above zero?

Thanks,

Dick Moores