| Singly linked list (SLL)                                                                                                | Doubly linked list (DLL)                                                                                                                                                                                |
| ----------------------------------------------------------------------------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| SLL nodes contains 2 field -data field and next link field.                                                             | DLL nodes contains 3 fields -data field, a previous link field and a next link field.                                                                                                                   |
| ![linkedlist](https://media.geeksforgeeks.org/wp-content/cdn-uploads/gq/2013/03/Linkedlist.png)                         | ![dll](https://media.geeksforgeeks.org/wp-content/cdn-uploads/gq/2014/03/DLL1.png)                                                                                                                      |
| In SLL, the traversal can be done using the next node link only. Thus traversal is possible in one direction only.      | In DLL, the traversal can be done using the previous node link or the next node link. Thus traversal is possible in both directions (forward and backward).                                             |
| Supports lesser number of operations in constant time                                                                   | Supports additional operations like insert before, delete previous, delete current node and delete last in O(1) time. Since it supports delete last, it is used to efficiently implement Deque.         |
| The SLL occupies less memory than DLL as it has only 2 fields.                                                          | The DLL occupies more memory than SLL as it has 3 fields.                                                                                                                                               |
| Complexity of deletion with a given node is O(n), because the previous node needs to be known, and traversal takes O(n) | Complexity of deletion with a given node is O(1) because the previous node can be accessed easily                                                                                                       |
| A singly linked list consumes less memory as compared to the doubly linked list.                                        | The doubly linked list consumes more memory as compared to the singly linked list.                                                                                                                      |
| Singly linked list is relatively less used in practice due to limited number of operations                              | Doubly linked list is implemented more in libraries due to wider number of operations. For example [Java LinkedList](https://www.geeksforgeeks.org/linked-list-in-java/) implements Doubly Linked List. |