Pointers store memory addresses of variables:

var x int = 42
var p *int = &x  // p points to x

fmt.Println(*p)  // Dereference: prints 42
*p = 21          // Change value through pointer
fmt.Println(x)   // prints 21

// Zero value of pointer is nil
var ptr *int
if ptr == nil {
    fmt.Println("Pointer is nil")
}