This new feature, found in Google Calendar's settings, aims to allow users to prevent third-party apps from viewing their Google Calendar events, even if those apps have general calendar access.

When you give an app calendar permissions it can tap into Android’s Calendar Provider API to access schedule data that’s synced with your device. That could come from anything like Samsung ...

Google Calendar users can now set reminders on the app's Web version, which will also sync with other reminders made from Keep, Inbox, and Google Now.

The Calendar API now supports push notifications - alerts sent directly to devices and apps instead of waiting for a client-side sync, a la Gmail - for updates that are practically instantaneous.

Google Tasks entries were already a part of Google Calendar's website, but now they're integrated with the Calendar apps on Android and iOS as well.