What is the method of gaining access to variables from the outer scope inside an anonymous function called?

In Go, the way to access variables from an outer scope inside an anonymous function is called a closure. An anonymous function 'closes over' variables from the surrounding context, allowing it to use and modify them.

Example:

func main() {
    x := 10
    f := func() {
        fmt.Println(x) // access to outer variable x
    }
    f() // will print 10
}

Thus, closures allow maintaining state and working with variables outside the local scope of the anonymous function.