Nothing against the other answers, but I found the brief explanation in the docs more easily understandable than the examples in them:
func append
func append(slice []Type, elems ...Type) []Type
The append built-in function appends elements to the end of a slice. If it has sufficient capacity, the destination is resliced to accommodate the new elements. If it does not, a new underlying array will be allocated. Append returns the updated slice. It is therefore necessary to store the result of append, often in the variable holding the slice itself:slice = append(slice, elem1, elem2) slice = append(slice, anotherSlice...)
As a special case, it is legal to append a string to a byte slice, like this:
slice = append([]byte("hello "), "world"...)