What is Push Notification in windows phone 7?

Question

What is meant by push notification in windows phone 7? and what are the types of push notification like local device notification or server side notification?

Answer 1

Push notifications are sent by the PNS (Push Notification Service) to devices in response to a request by your web server on a channel that your app created on the device and sent to the web service....

That's all a bit of a mouthful, but is the essence of it.

For an overview, checkout this online documentation

Push Notifications for Windows Phone

and for the different types..

Types of Push Notifications for Windows Phone

and coverage in Peter Torr's Mix 10 Talk, CL17 - 28 minutes in