--- title: Demystifying async/await in C#: The Hidden State Machine description: The C# compiler transforms async/await methods into state machines behind the scenes. When you mark a method as async, the compiler generates a struct... canonical: https://daily.dev/posts/demystifying-async-await-in-c-the-hidden-state-machine-ej0npqym4 twitter:card: summary_large_image twitter:site: @dailydotdev og:type: website og:site_name: daily.dev og:title: Demystifying async/await in C#: The Hidden State Machine | daily.dev og:description: The C# compiler transforms async/await methods into state machines behind the scenes. When you mark a method as async, the compiler generates a struct... og:url: https://daily.dev/posts/demystifying-async-await-in-c-the-hidden-state-machine-ej0npqym4 og:image: https://api.daily.dev/og/posts/ej0NpqYM4.png og:image:alt: Demystifying async/await in C#: The Hidden State Machine og:image:width: 1200 og:image:height: 630 og:locale: en --- > ## Documentation Index > Fetch the complete documentation index at: https://daily.dev/llms.txt > Use this file to discover all available pages before exploring further. # Demystifying async/await in C#: The Hidden State Machine **[C\# Corner](https://daily.dev/sources/csharpcorner)** · 3 min read · 0 upvotes · 0 comments ## Summary The C# compiler transforms async/await methods into state machines behind the scenes. When you mark a method as async, the compiler generates a struct implementing IAsyncStateMachine that tracks execution state, captured local variables, and a method builder. The original method becomes a stub that initializes this state machine. The MoveNext() method uses a switch statement to resume execution at the correct point after an await. When async methods complete synchronously, the state machine stays on the stack with no heap allocation; boxing only occurs when execution truly pauses. This transformation explains why locals are captured as fields, enables zero-allocation fast paths, and provides efficient non-blocking operations while maintaining readable, sequential code. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: ## Similar posts on daily.dev - [Runtime Async in .NET 11: What Actually Changed](https://daily.dev/posts/runtime-async-in-net-11-what-actually-changed-zpn3rqvrg) · C\# Corner · 13 upvotes · 0 comments - [Async or Swim: The Complete Guide to Asynchronous .NET](https://daily.dev/posts/async-or-swim-the-complete-guide-to-asynchronous-net-n2fszfnf6) · ITNEXT · 9 upvotes · 1 comments - [How async, await and Task are related in C\#?](https://daily.dev/posts/how-async-await-and-task-are-related-in-c--td1oloovi) · C\# Corner · 25 upvotes · 0 comments --- Tags: [#performance](https://daily.dev/tags/performance), [#.net](https://daily.dev/tags/.net), [#c#](https://daily.dev/tags/c#), [#compiler](https://daily.dev/tags/compiler) [View this post on daily.dev](https://daily.dev/posts/demystifying-async-await-in-c-the-hidden-state-machine-ej0npqym4) ```json {"@context":"https://schema.org","@graph":[{"@type":"Organization","@id":"https://daily.dev/#organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180},"sameAs":["https://twitter.com/dailydotdev","https://github.com/dailydotdev","https://www.linkedin.com/company/daily-dev-ltd"]},{"@type":"WebSite","@id":"https://daily.dev/#website","url":"https://daily.dev","name":"daily.dev","publisher":{"@id":"https://daily.dev/#organization"},"potentialAction":{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https://daily.dev/search?q={search_term_string}"},"query-input":"required name=search_term_string"}}]} {"@context":"https://schema.org","@type":"TechArticle","headline":"Demystifying async/await in C#: The Hidden State Machine","url":"https://daily.dev/posts/demystifying-async-await-in-c-the-hidden-state-machine-ej0npqym4","mainEntityOfPage":{"@type":"WebPage","@id":"https://daily.dev/posts/demystifying-async-await-in-c-the-hidden-state-machine-ej0npqym4"},"datePublished":"2026-01-26T08:43:49.114Z","dateModified":"2026-01-26T08:44:08.625Z","description":"The C# compiler transforms async/await methods into state machines behind the scenes. 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