To enable the Automatic Updates feature:


Thereafter, whenever your computer is connected to the Internet, but not doing something for you, it will automatically download critical updates. Each critical update you completely download will be installed automatically at the time you've specified.
What this means is that your web browsing experience will not be affected. For example, while you are reading a web page, updates will download. When you click a link, or do something else that moves you to another page, the download will pause while the new page downloads. The critical update download will then resume.
If a restart of your computer is required, it will be done automatically.