What are the scenarios in which we use XML in asp.net

Below may be some scenarios
1) Forwarding customer orders to vendors for processing without knowing the s/w program vendor is using to process order.

2) Exchanging data b/w multiple application with multiple p/f.
e.g exchanging data b/w asp.net website and iPhone application

3) You want to insert one to many relationship data in data base. Here you need to buid xml string to sent at database.