Modern Python Standard Library Cookbook

How it works...

Our counting code relies on the fact that Counter is just a special kind of dictionary, and that dictionaries can be built by providing an iterable. Each entry in the iterable will be added to the dictionary.

In the case of a counter, adding an element means incrementing its count; for every "word" in our list, we add that word multiple times (one every time it appears in the list), so its value in the Counter continues to get incremented every time the word is encountered.