The append() method adds a single element to the end of a list. Given fruits = ["apple", "banana"], calling fruits.append("cherry") modifies the list to ["apple", "banana", "cherry"].
Note that append() modifies the list in place and returns None. Don't write fruits = fruits.append("cherry") as that sets fruits to None. The method takes exactly one argument, but that argument can be anything.
Including another list: fruits.append(["grape", "melon"]) creates a nested list: ["apple", "banana", "cherry", ["grape", "melon"]]. Use append() when building lists incrementally, one item at a time.