If you've upgraded to macOS Mojave or later, follow these steps to keep it up to date:

Choose System Preferences from the Apple menu , then click Software Update to check for updates.

If any updates are available, click the Update Now button to install them. Or click ”More info” to see details about each update and select specific updates to install.

When Software Update says that your Mac is up to date, the installed version of macOS and all of its apps are also up to date. That includes Safari, iTunes, Books, Messages, Mail, Calendar, Photos, and FaceTime.

To find updates for iMovie, Garageband, Pages, Numbers, Keynote, and other apps that were downloaded separately from the App Store, open the App Store on your Mac, then click the Updates tab.

To automatically install macOS updates in the future, including apps that were downloaded separately from the App Store, select ”Automatically keep my Mac up to date.” Your Mac will notify you when updates require it to restart, so you can always choose to install those later.