Mac Desktop Software Update

First, identify your model Mac: Find your Mac model name and serial number - Apple Support, and then Find out which macOS your Mac is using - Apple Support to determine its macOS version eligibility.

• Please don't post any serial numbers to this site.

You posted in the iMac forum, and said that your computer is about 10 years old. You need to determine the exact age (the hardware model and model year) more precisely, as that is what determines how far you can upgrade.

It this is an iMac all-in-one desktop …

• from 2013 – Catalina is the end of the line
• from 2014 or mid 2015 – Big Sur is the end of the line
• from late 2015 – Monterey is the end of the line
• from 2017 – Ventura is the end of the line (unless it is a Xeon-based iMac Pro; then it can run Sequoia)

How to download and install macOS - Apple Support

Earlier MacBooks have been already marked as obsolete, So there will be no service or no updates for this models.

Better to upgrade you MacBook for better functionality .