Okay, following up on the previous lecture, let's see what types of data can be stored in memory and used inside Python applications. The python programming language defines many types of data for many types of operations, we will have a look at the most widely used data types starting with this lecture. As an overview, let's enumerate the most famous and useful Python three data types. So we have strings, numbers, Booleans, lists, sets, frozen sets, topples, ranges, dictionaries, and the non type. All these data types are built in into the Python programming language core. And you will see that they are very clearly defined and easy to use.

One way to classify data types is by whether the object A data type can be modified after creation or not. This is called mutability, or immutability, respectively. So this leads to two kinds of data types, mutable data types, which can be modified after creation. Here we can mention lists, dictionaries, and sets, for instance, and immutable data types. Here we have strings, numbers, topples, and frozen sets, for example. So remember, if you have an object of an immutable type, you cannot change the contents of that object in any way, shape or form.

You will just have to create another object with the content that you want. Now it's time to have a closer look at the data type we already talked about earlier in the course strings.