The jobs command we were using earlier only lists processes that were started from your bash session. To see all the processes on your system, use ps with the a and x options together:

$ ps ax
  PID TTY      STAT   TIME COMMAND
    1 ?        S      0:04 init [3]
    2 ?        SW     0:11 [keventd]
    3 ?        SWN    0:13 [ksoftirqd_CPU0]
    4 ?        SW     2:33 [kswapd]
    5 ?        SW     0:00 [bdflush]

We've listed only the first few because it's usually a very long list. This gives you a snapshot of what the whole machine is doing, but it is a lot of information to sift through. If you were to omit the ax, you would see only processes that are owned by you, and that have a controlling terminal. The command ps x would show you all your processes, even those without a controlling terminal. If you were to use ps a, you would get the list of everybody's processes that are attached to a terminal.