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    <p>No, <code>await</code> is <em>not</em> like just calling <code>get()</code>. There's <em>considerably</em> more to it.</p> <p>When you use an <code>await</code> expression in C#, the compiler effectively creates a continuation, so that if the awaitable hasn't completed yet, the method can immediately return, and continue processing only when it's completed. The continuation will run in an appropriate context - so if you're on a UI thread before the <code>await</code> expression, you'll continue on the UI thread afterwards, but without blocking the UI thread while you're waiting for the result. For example:</p> <pre><code>public async void HandleButtonClick(object sender, EventArgs e) { // All of this method will run in the UI thread, which it needs // to as it touches the UI... however, it won't block when it does // the web operation. string url = urlTextBox.Text; WebClient client = new WebClient(); string webText = await client.DownloadStringTaskAsync(url); // Continuation... automatically called in the UI thread, with appropriate // context (local variables etc) which we used earlier. sizeTextBox.Text = string.Format("{0}: {1}", url, webText.Length); } </code></pre> <p>Ultimately it's all syntactic sugar, but <em>much</em> more complicated sugar than what you've shown.</p> <p>There's a lot of detailed information available on the web already. For example:</p> <ul> <li><a href="http://blogs.msdn.com/b/ericlippert/archive/tags/async/" rel="nofollow noreferrer">Eric Lippert's blog</a></li> <li>The <a href="http://msdn.microsoft.com/en-us/vstudio/gg316360" rel="nofollow noreferrer">Visual Studio async home page</a></li> <li><a href="https://codeblog.jonskeet.uk/category/async/" rel="nofollow noreferrer">My own blog posts about async</a></li> </ul>
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    1. COBut if you don't care which thread runs what, isn't it effectively equivalent. Continuation on line 12, is equivalent to having a thread blocking on line 12, isn't it? The only gain is to have everything running on the same thread, which is usually useful only because the UI thread is privileged. Am I correct?
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    2. CO@Chi-Lan: Not really. Suppose you have a server which is meant to implement long polling, so may have hundreds of thousands of active connections. At that point you *really* don't want the thread-per-request model, so you can't block waiting for "whatever's going to trigger a response". So you need to have *some* sort of continuation mechanism - and the language support in C# 5 makes that really simple; it lets you write code which looks and feels like the synchronous code we're relatively good at writing, but with asynchronous properties.
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    3. COhmmm... got you. It's equivalent to the lightweight/green threads model we see popping around lately, eg golang.org with the ability to mark which real thread do you want to run your coroutine. Am I correct now, eventually?
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