What are singly linked lists and doubly linked lists? 

What are singly linked lists and doubly linked lists? 

A singly linked list is a linear data structure where each element is a separate object, called a node. Each node contains two fields:

1. Data: Stores the actual value or data.
2. Next: A pointer/reference to the next node in the sequence.

In a singly linked list, each node points to the next node, and the last node points to NULL, indicating the end of the list.