Updating OS X
My Macbook Pro (Mid 2014) is presently running on OS X Yosemite. It has not asked me to update in a long time. Should I update, and if so, how?
Updates are applied to keep the same major version completely up-to-date.
If you would like to use a more recent version of MacOS, you will need to UPGRADE (like a purchase, but on sale for $0).
How to upgrade to macOS High Sierra - Apple Support
Mojave transitions to Metal imaging model and has additional features. Catalina is also available, but has the disadvantage that a lot of older software is no longer supported.
How to upgrade to macOS Mojave - Apple Support
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