Async class can use when an Applications that perform many tasks simultaneously, yet remain responsive to user interaction, often require a design that uses multiple threads. Such as Facebook messenger which works on website and in app also where you can access same chats.
Go through the below links for more reference on Asynch and Await :
Hope this will help you.
DNS Gold Member
"Failure is the path of least persistence"
Async programming is highly faster when compared to normal programming with normal classes normal methods.
It takes time for a normal method to return result.
Async methods will contain Task<datatype> as return type.
async Task<int> some_Method()
Go through below links for more reference
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