Activity Monitor - what does it measure

hi
Just interested but I have opened activity monitor and its on my toolbar. Could anyone explain what is meant by private memory/real memory/shared/virtual private and virtual.Thanks steve

Not sure about "private memory" or "shared" or "virtual private" (but then I'm using OS 10.3.9 - Panther).
Real memory is exactly that, the portion of physical RAM being used by any one of the activities listed in the window.
Virtual memory is the amount of RAM being allocated to the OS - by the OS - from your hard drive, thus keeping physical RAM use within boundaries (and preventing overload, with subsequent crashes and kernel panics).

It's a fascinating exercise watching the progress of Activity as more or less is used by the OS. For example, since I started typing this response, AppleSpell kicked into action, showing me spelling or typing errors, and unknown words, within this text.

Activity monitor measures the amount of CPU potential you're using, the RAM you and the system are using, time reactions between the computer and hardware. It takes a little time to figure it all out. If you're impatient, download the iStat or iStat nano widget from the widget downloads center.