f2db8a79_OS_X_Tips_Tweaks_and_Tutorials__What_the_data_means
[Subcategory] Available [What the data means] 
Reports on the total amount of RAM, in kilobytes, currently available. When available RAM is used up, your system begins to use its Page File.
Windows Task Manager – Performance Monitoring Explained | Windows Vista,XP, Linux and OS X Tips,Tweaks and Tutorials
What the data means