# 2.2 Associative Structures

You’ve also probably encountered associative structures before; in Python, a *dictionary* is a great example! An associative structure can be thought of as a way to *group* different data together.

## Tuples

A tuple is an *immutable* data structure that is similar to a Python list with fixed length. They are often referred to as *n-tuples*, where *n* is the number of elements that tuple contains.

## Maps

A map is a *mutable* data structure; you can think of a map as a list of pairs (2-tuples). Maps can also be thought of as a function in the mathematical sense – a map *maps* a *domain* to a *range*.