We very often get asked: ‘How do you find out what Operating System you are running on your Mac?’ To find this out, click on the symbol in the top-left of your screen and choose ‘About This Mac’.
If you are running the latest system, it will say MacOS High Sierra, of which the latest version is 10.13.3.
Should this not be the case, go to the App Store and click on updates. You need to ensure that you do this regularly. For example, the latest 10.13.3 update contains a fix for a modern CPU performance feature which Meltdown and Spectre can take advantage of, which has been widely reported in the media recently.
