If your Mac is using an earlier version of any Mac operating system, you should install the latest Apple software updates, which can include important security updates and updates for the apps that are installed by macOS, such as Safari, Books, Messages, Mail, Music, Calendar, and Photos.

• The best Mac OS version is the one that your Mac is eligible to upgrade to. In 2021 it is macOS Big Sur. However, for users that need to run 32-bit apps on Mac, the best macOS is Mojave. Also, older Macs would benefit if upgraded at least to macOS Sierra for which Apple still releases security patches. How to Tell Which macOS You Are Running.
• At the time of writing, the current version of macOS is Catalina (10.15.x), and the two previous versions are Mojave (10.14.6) and macOS High Sierra (10.13.6). Keep in mind that even though these two older macOS versions still receive security updates, not all known vulnerabilities are addressed.

Is your Mac up to date with the latest version of the Mac operating system? Is it using the version required by some product that you want to use with your Mac? Which versions are earlier (older) or later (newer, more recent)? To find out, learn which version is installed now.

If your macOS isn't up to date, you may be able to update to a later version.

Which macOS version is installed?

From the Apple menu  in the corner of your screen, choose About This Mac. You should see the macOS name, such as macOS Big Sur, followed by its version number. If you need to know the build number as well, click the version number to see it.

Which macOS version is the latest?

These are all Mac operating systems, starting with the most recent. When a major new macOS is released, it gets a new name, such as macOS Big Sur. As updates that change the macOS version number become available, this article is updated to show the latest version of that macOS.

Should You Upgrade From High Sierra To Mojave

If your Mac is using an earlier version of any Mac operating system, you should install the latest Apple software updates, which can include important security updates and updates for the apps that are installed by macOS, such as Safari, Books, Messages, Mail, Music, Calendar, and Photos.

Can You Upgrade From High Sierra To Mojave