View your Mac’s memory use.
Click Memory in the Activity Monitor window to see the following:
Physical Memory: The amount of RAM installed.
Memory Used: The amount of RAM being used and that’s immediately available.
Virtual Memory: The amount of disk or flash drive space being used as virtual memory.
Swap Used: The amount of space on your hard drive being used to swap unused files to and from RAM.
App Memory: The amount of space being used by apps.
File Cache: The space being used to temporarily store files that aren’t currently being used.
Wired Memory: Memory that can’t be cached to disk, so it must stay in RAM. This memory can’t be borrowed by other apps.
Compressed Mem: The amount of memory in RAM that’s compressed.
When you computer approaches its maximum memory capacity, inactive apps in memory get compressed, making more memory available to active apps. The Compressed Mem column indicates the amount of memory compressed for an app.
Memory Pressure: Graphically represents how efficiently your memory is serving your processing needs.
Memory pressure is determined by the amount of free memory, swap rate, wired memory, and file cached memory.
To make more columns visible, choose View > Columns.
You can use Activity Monitor to determine if your Mac could use more RAM.