Adding Elements: append()

Lists come with handy tools for common tasks, called methods. A method is a function that belongs to a value. You don't write the value in the parentheses, as with len(students). You write it before the method's name, followed by a dot: students.append("Tom"). Using a function or a method is called calling it.

The method append() adds an element to the end of a list. You write the new element in the parentheses:

car_brands = ["Mercedes", "Cadillac"]
car_brands.append("Volvo")
print(car_brands)
print(len(car_brands))

This prints:

['Mercedes', 'Cadillac', 'Volvo']
3

Read car_brands.append("Volvo") from left to right: for the list car_brands, call the method append(), which adds "Volvo" to its end. The list changes, and so does its length.

This way, you can also build a list step by step, starting from an empty list:

todo = []
todo.append("Buy milk")
todo.append("Walk the dog")
print(todo)

This prints:

['Buy milk', 'Walk the dog']

Method names are case-sensitive, just like variable names. If you write car_brands.Append("Volvo"), the program stops with AttributeError: 'list' object has no attribute 'Append'. Did you mean: 'append'? An attribute is anything that belongs to a value and is written after a dot. A list has no Append, and Python even suggests the right name.