Alerts, alarms, reminders, email—chances are you see a steady stream every day. Notification Center is Sierra’s Grand Central Station for the information competing for your attention. Its settings control which apps can post messages to the upper-right corner of your display, as well as how those messages look. The Notification Center sidebar, which slides in from the right of your screen, gives you an overview of it all.
Sierra updates Notification Center’s look and integrates it with Siri, letting you pin (attach) your most-checked Twitter feeds, sports schedules, and more to it ①.