• Built-in module to implement specialised container datatypes.

List of Module

1. DefaultDict
2. OrderedDict
3. Counter
4. ChainMap
5. NamedTuple
6. Deque
7. UserDict
8. UserList
9. UserString

DefaultDict :

Referenced form Geeks For Geeks

• subclass to the dictionary object in python
• provides default values to keys so as not to raise keyerror
• Syntax :

class collections.defaultdict(default_factory)

• very first argument of DefaultDict is default_factory
• this is only a syntax, when I say its required to put a default factory argument, I mean put in anything that can be returned as a default value.