We've already encountered some of the built-in collections

• str – the immutable string sequence of Unicode code points

• list – the mutable sequence of objects

• dict – the mutable dictionary mapping from immutable keys to mutable
  objects

We've only scratched the surface of how these collections work, so we'll explore their powers in greater depth in this chapter. We'll also introduce three new built-in collections types:

• tuple - the immutable sequence of objects

• range - for arithmetic progressions of integers

• set - a mutable collection of unique, immutable objects

We won't cover the bytes type any further here. We've already discussed its essential differences with str, and most of what we learn about str can also be applied to bytes.

This is not an exhaustive list of Python collection types, but it's completely sufficient for the overwhelming majority of Python 3 programs you'll encounter in the wild or are likely to write yourself.

In this chapter we'll be covering these collections in the order mentioned above, rounding things off with an overview of the protocols that unite these collections and which allow them to be used in consistent and predictable ways.