One of the most fundamental design elements of the Python language is its use of objects. Objects are the central data structure not only of user-level constructs but also many of the inner workings of the language itself. In this chapter we'll start to to develop a sense of what this means, both in principle and in practice, and hopefully you'll start to appreciate just how pervasive objects are throughout Python.

We'll take a look at what objects are, how you use them, and how you manage references to them. We'll also start to explore the notion of types in Python, and we'll see how Python's types are both similar to and different from those in many other popular languages. As part this exploration we'll take a more in-depth look at some collection types we've met already, and introduce a few more collection types as well.