What does "About This Mac" tell me?

Selecting About This Mac from the Apple menu opens a window which provides the following information:

• The version of the Mac OS currently running on the system.(Version)
• The type of processor(s) in the computer.(Processor)
• The amount of physical RAM in the computer.(Memory)
• The disk the computer from with the computer has been started.(Startup Disk)

Clicking on the Version field will reveal the build number for the version of the Mac OS currently installed and running on the computer. Clicking a second time will reveal the serial number for the computer.

Other information about the system can be obtained by clicking on the More Info... buttton in that window.