[dba-SQLServer] Logical reads/writes

I suppose that I should know what these terms mean, but the fact is that I
don't.  I'm looking at this report of object execution times from SQL 2005
and  there are columns about logical reads and writes and I have no idea
what that means. Logical as opposed to physical, or as opposed to illogical?
Oh and then there is Total Logical IO. That would be a really funny graph if
they had Illogical Reads and Writes LOL.

It's time to Google, I guess.

Arthur