As well as releasing the iOS 9.2.1 update for the iPhone and iPad, Apple has also released a new software update for the Mac, OS X 10.11.3 El Capitan.
The OS X 10.11.3 El Capitan comes with a range of performance, stability and security improvements for Mac OS, you can see what is included in the update below.
• Fixes an issue that may prevent some Mac computers from waking from sleep when connected to certain 4K displays.
• Third-party .pkg file receipts stored in /var/db/receipts are now retained when upgrading from OS X Yosemite.
For detailed information about the security content of this update, see Apple Security Updates.
You can download the OS X 10.11.3 El Capitan software update from the Mac App store and you can find out full details on what is included in the update at the link below.