Like Lists, Dictionaries are mutable. This means they can be changed after they are created. One advantage of this is that we can add new key/value pairs to the dictionary after it is created like so:

dict_name[new_key] = new_value

An empty pair of curly braces {} is an empty dictionary, just like an empty pair of [] is an empty list.

The length len() of a dictionary is the number of key-value pairs it has. Each pair counts only once, even if the value is a list. (That’s right: you can put lists inside dictionaries!)