Async/Await in C# (Interview Guide)

Most developers fail this question — not because they don’t know async/await, but because they explain it poorly.

What is async/await in C#?

❌ Bad answer

It makes code asynchronous.

✅ Senior answer

Async/await allows you to write asynchronous code in a non-blocking way. When awaiting an operation, the thread is freed to handle other work instead of being blocked.

How it works under the hood

Uses Task-based Asynchronous Pattern (TAP)
Compiler transforms code into a state machine
Execution resumes when the awaited task completes

Common mistakes

❌ Blocking async code

var result = GetDataAsync().Result;

This can cause deadlocks.

✅ Correct usage

var result = await GetDataAsync();

⚠️ ConfigureAwait(false)

await SomeAsync().ConfigureAwait(false);

Avoids capturing synchronization context in library code.

Example

public async Task<string> GetDataAsync()
{
    var response = await httpClient.GetAsync("https://api.com");
    return await response.Content.ReadAsStringAsync();
}

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