On the other hand, by default, most OS X system and Mac App Store updates are automatically downloaded in the background but not installed.In this case, when updates are ready to be installed, a Mac App Store notification displays, stating “Updates Available.” From this notification you can click Install or Restart, which will immediately install the updates and restart the computer if necessary.If the update items have already been downloaded, a notification displays.
This chapter from OS X Support Essentials 10.11 - Apple Pro Training Series: Supporting and Troubleshooting OS X El Capitan shows you how to configure automatic software update settings, automatically update Apple-sourced software, and manually update Apple software.
Adding new capabilities is the very reason “software” exists.
For most users, Mac App Store software updates require appropriate Apple ID authentication.
If you have not previously signed in to the Mac App Store from the computer you’re working on, you will be required to authenticate with an Apple ID.
For that reason, OS X includes an easy-to-use software update mechanism that automatically checks the Apple servers via the Internet to make sure you’re running the latest Apple-sourced software.
Automatic software update checking is enabled by default as soon as you start using your Mac.If none of the updates requires a restart for installation, the software automatically installs without any further interaction.However, if any of the updates requires a restart after the install process, you are given the option to restart or again defer the installation.After deferring updates, when you are ready to install updates or want to manually check for new updates, you can do so at any time using the following methods: TIP When software updates are available, a number badge (indicating the number of available updates) will appear next to the Mac App Store icon, the Mac App Store toolbar Updates button, and the Mac App Store selection in the Apple menu.Also, when you try to restart or shut down the computer, you may be reminded to install available updates.Both automatic and manual software updates require an Internet connection to download update installers.