What is the difference between Task.Delay and Thread.Sleep in C#?

Question

Accepted Answer

**Task.Delay** — non-blocking. **Thread.Sleep** — blocking.

**Task.Delay:**
- Non-blocking.
- Returns Task.
- Can be awaited.
- Doesn't block thread.

```csharp
// Non-blocking
await Task.Delay(1000);
Console.WriteLine("After 1 second");
```

**Thread.Sleep:**
- Blocking.
- Returns void.
- Blocks entire thread.

```csharp
// Blocking
Thread.Sleep(1000);
Console.WriteLine("After 1 second");
```

**In async code, always use Task.Delay:**
```csharp
// Bad
async Task DoWork() {
    Thread.Sleep(1000);  // Blocks thread!
}

// Good
async Task DoWork() {
    await Task.Delay(1000);  // Non-blocking
}
```

C#: What is the difference between Task.Delay and Thread.Sleep in C#?