About This Mac
From Mac Guides
About This Mac is a menu item found in the Apple menu. Its purpose is to provide a quick and basic overview of your system.
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Functions
You can click on the buttons to get a more detailed view of your computer using System Profiler or check for available software updates. Clicking on the Version number will show the installed OS X build number and another click will show your machine's Serial Number.
Prior to Mac OS X this window was named "About This Computer" and contained RAM statistics. The information used to be vital in deciding memory allocations, finding programs with memory leaks and dealing with RAM fragmentation.
