Asynchronous programming is the default style for most applications. Anything that has a GUI is bound to be asynchronous, as is anything that uses event handling. In most cases you can just ignore the fact that you are working asynchronously and write event handlers without worrying about blocking the thread that makes everything work. There comes a time, however, when an operation typically takes so long that blocking the thread isn't an option and so you need to recognize the fact that your code is executing in an asynchronous  environment.

The usual solution is to run the code in a non-blocking mode and use a callback - but this is horribly messy. The new facilities in C# 4.0 for asynchronous programming - the Async CTP - allow you to hide the callbacks in syntactic sugar - and this is really good. It makes your code read more like the order of execution suggests it should and this makes it more meaningful, easier to understand and hence less likely to harbor bugs.

If you would like a painless introduction to the Async CPT then take a look at the videos below produced by the Async team and posted on MSDN. The two sets are identical except one uses C# and the other VB. Each video is around five minutes in length.

If you prefer reading about the Async CTP then see our introductory article: Async, Await and the UI problem.

Visual C#

Introduction to the Async CTP

Offloading Work with TaskEx.Run

Polling and Cancellation

Refactoring Functionality into a Library

Visual Basic

Introduction to the Async CTP

Polling and Cancellation

Offloading Work with TaskEx.Run

Concurrent Downloading with TaskEx.WhenAll

Refactoring Functionality into a Library

More information

Async, Await and the UI problem

The videos on MSDN

The Async forum on MSDN

The Async CTP home page