What is context in Go?

Question

Accepted Answer

**Context** — carries deadlines, cancellation, and request-scoped values.

**Key features:**
- Cancellation.
- Timeouts.
- Deadlines.
- Request-scoped values.

```go
// Create context with timeout
ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
defer cancel()

// Use in HTTP request
req, _ := http.NewRequestWithContext(ctx, "GET", "https://api.example.com", nil)
```

**Cancellation:**
```go
ctx, cancel := context.WithCancel(context.Background())

go func() {
    for {
        select {
        case <-ctx.Done():
            fmt.Println("Cancelled")
            return
        default:
            // Do work
        }
    }
}()

cancel()  // Cancel the context
```

**Best practices:**
- Pass context as first parameter.
- Don't store context in struct.
- Always call cancel().
- Use context.Background() only at root.

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