Check what version of OS X your Mac is running, because knowledge is power.
Click on the Apple logo in the top left corner of your screen. It should look like this .
Click on About This Mac.
As you can see in the picture below, you will see the name of the OS X version right at the top, and under that will be the version number. In this case, you can see the Mac is running OS X El Capitan version 10.11.5.
The tabs across the top will provide you with additional information about your Mac’s display and attached displays, storage, and support and service. Additionally, the “System Report…” button at the bottom will open the System Information app with detailed information about all of your Mac’s hardware and software bits, while “Software Update…” will open the Mac app Store and check for available updates to OS X.
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