Can you explain the mechanism of adding an element to the end of a data structure, such as a list or array?

In Go, to add an element to the end of a slice, the built-in append function is used. Slices are dynamic structures that can change size.

Example:

package main
import "fmt"

func main() {
    nums := []int{1, 2, 3}
    nums = append(nums, 4) // add 4 to the end
    fmt.Println(nums) // [1 2 3 4]
}

If the slice does not have enough capacity, append will create a new array with increased size, copy the old elements, and add the new one. Arrays in Go have a fixed size, so slices are used for dynamic addition.