Physical Memory in Windows Task Manager

Question

In Windows Task Manager under the Perofrmance tab, I see this under Physical Memory:

Total 3582 
Cached 867 
Available 846
Free 11

How come the numbers don't add up to the total? What is the difference between free memory and available memory?

Answer 1

From Microsoft's Description of What the Available Bytes in Task Manager Represents :

If you do not understand what this "Available Memory" counter actually represents, it may appear that it never approaches zero at times when you might expect it to do so.

The "Available Memory" counter in Task Manager is actually the sum of the following three internal memory lists:

• The Standby list.
• The Free list.
• The Zero list.

See the above article for an explanation of what these lists mean.