What a doubly linked list is
A doubly linked list is a kind of linked list in which each node holds links to both the next node and the previous node. In a basic linked list, each node points only forward to the next one. A doubly linked list adds a backward link as well, so you can move through the list in both directions, forward and backward.
Links in both directions
The defining feature of a doubly linked list is that every node has two links: one to the node after it and one to the node before it. These two-way connections form a chain that can be followed either way. This is different from a singly linked list, where the chain can only be followed in one direction because each node points just to the next.
Traversing forward and backward
Because each node links both ways, a doubly linked list can be traversed starting from either end and moving in either direction. From any node, you can go to the next node or back to the previous one. This two-way movement is convenient for operations that need to look backward as well as forward, which a singly linked list cannot do directly.
Inserting and removing nodes
The backward links also help when inserting or removing nodes, because from a given node you can directly reach its neighbor on either side and update the links accordingly. This makes certain changes to the list more convenient than in a singly linked list. The trade-off is that each node must store an extra link, using a bit more space.
Why doubly linked lists matter
Doubly linked lists matter because the ability to move in both directions makes them well suited to many tasks, from navigating back and forth through items to efficiently editing a sequence. They are a common variation of the linked list. Understanding the doubly linked list clarifies how adding a backward link expands what a linked structure can do.
Why it matters
The doubly linked list is a fundamental data structure. Understanding what it is - a linked list with both forward and backward links - clarifies how programs store sequences that can be traversed in either direction. For anyone interested in computer science, it is a valuable concept to understand.
Related on Skillo
See also: What is a linked list? Explained, What is a data structure? Explained.
Sources
Published date reflects the original event date (2026-10-18). This article is original Skillo editorial written from the sources above; facts were verified in September 2026.
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