Explain what a doubly linked list data structure is and what its features are.

A doubly linked list is a data structure consisting of nodes, where each node contains data and two references:

• to the next element in the list (next),
• to the previous element in the list (prev).

Features of a doubly linked list:

• Allows efficient traversal both forward and backward through the list.
• Convenient for insert and delete operations in the middle of the list, as neighboring nodes can be easily accessed.
• Requires more memory compared to a singly linked list due to storing two pointers.

Example of a node in C++:

struct Node {
    int data;
    Node* prev;
    Node* next;
};