Mutability, simply put: the contents of a mutable object can be changed, while the contents of an immutable object cannot.

Simple Types

All of the simple data types we covered first are immutable.

You can replace the value, but you can’t change it.

type use mutable?
int, float, decimal store numbers no
str store strings no
bool store True or False no

Container Types

For the mutability of the container types we covered next, check this helpful list:

container type use mutable?
list ordered group of items, accessible by position yes
set mutable unordered group consisting only of immutable items. useful for set operations (membership, intersection, difference, etc) yes
tuple immutable collection containing ordered groups of items no
dict contains key value pairs yes