Apple’s common system for differentiating its various models in a given computer line is a bit unique, where instead of appending a collection of letters and/or numbers to a model as it did in the past (e.g. Performa 675), it now uses a segment of the year in which the model was introduced, such as the “mid-2012” version, or the “late-2013” model, or finally the “early-2014” model.
If you need to service your system, or update it, then you may need to know this detail about it in order to get the appropriate parts and upgrades, or even see if the latest version of OS X is compatible with it.
To do this, you just need to go to the Apple menu, choose About This Mac, and then click the “More Info” button. In the window that shows, you will see all of the necessary details for your system:
Since at times this sequential model notation is used to identify Mac systems, you can look it up in several ways. The first is to click the “system report” button in the window shown above, and then in the Hardware section see the ‘model identifier.”
The second option is to use the Terminal, where you can enter the following command to have the model identifier reported back to you: