The OS X 10.11.3 update for Mac has been released, today. The update is to improve the stability, compatibility, and security. Apple recommends this update to all Mac users with OS X El Capitan. In this update, there is also a fix an issue that may prevent some Mac computers from waking from sleep when connected to certain 4K displays. For the enterprises, this update useful when they do the upgrade from OS X Yosemite, third-party .pkg file receipts to be restored in /var/db/receipts. You can read about the security improvement in this update, here.
You can check this update through the App Store application in the Update tab, and there is also a reminder on your Mac that the OS X update is available.
Apple suggests you to backup all your data and system before you do the update. At this point, there is no information about the issue appear during and after the update. Moreover, Apple is also testing the OS X 10.11.4 Beta Public, where you can participate in this program. If you have participated this program before, the OS X 10.11.3 will not be available. So, are you ready to update?