Defer is a powerful feature in Go, which is similar to "finally" in other languages.

func main() {
	defer fmt.Println("Hello, World!")

	fmt.Println("Hello") 
}

The deferred call's arguments are evaluated immediately, but the function call is not executed until the surrounding function returns.

Defer works as a stack, deferred calls are executed in last-in-first-out order. (LIFO)

Defers are even executed when a panic occours

Use cases

• Cleaning up resources after an operations. E. g. closing files
• Measuring performance of a function
• Recovering from panics, as defer functions are still run in case of error. See: panic & recover

Next chapter: Errors