What is a Python defaultdict and when to use it?

Python has a datatype called dictionary (or dict) in which you can map values to keys. But you can also import the similar defaultdict datatype from the standard collections library.

What is a defaultdict in Python and when to use it? Image by catalyststuff on Freepik

A defaultdict is a dictionary that can be given a default value. Which means that when you try to work with a key that is not in the dictionary yet, a default value is used.