To upgrade an Apple Mac Operating System (macOS):

1. Click on the Apple menu 

2. Click on 'System preferences...'

3. Click on the ‘Software Update‘ application 

4. You can upgrade to the latest version of the operating system (the image here below shows the Monterey version) clicking on 'Upgrade Now'. This is a major update and can take several hours to complete. 

5. If there are more updates available, you will find the section 'Other updates are available'. Clicking on the 'More info' link, you will see all the updates available to your existing operating system. 

You can select whether you want to install all the updates available or only a part of them. Click on 'Install Now' to launch the process.

Please keep in mind that the process will take up to an hour to complete.

Please be aware:

• While installing the Operating System you will be unable to use your computer during the whole process
• Please ensure that you have a backup of all vital data before patching via either option

Useful links

How to open downloaded packages and disk images from an unidentified developer