USB port max current

I know it's 500ma for USB 2.0 (and 900ma for 3.0).
Now my question is: The 500ma load limit is for each USB port, or it's the sum of all the devices connected to all them?
Please enlighten me.

Rookie2:
I know it's 500ma for USB 2.0 (and 900ma for 3.0).
Now my question is: The 500ma load limit is for each USB port, or it's the sum of all the devices connected to all them?
Please enlighten me.

It is a limit for each individual Port connector, not the sum of all such ports on a PC. On a arduino board it is further enforced by a 500ma thermofuse in series with the USB +5vdc supply to the board.

Lefty

Really good news, thank you mate.