Is Linked List a Data Structure or ADT?


Larry Thompson

Is Linked List a Data Structure or ADT?

A linked list is a commonly used data structure in computer science. It is often used to implement other data structures and algorithms, such as stacks, queues, and hash tables.

However, it is important to understand that a linked list itself is not a data structure but an abstract data type (ADT). Let’s dive deeper into this topic.

What is an Abstract Data Type (ADT)?

An ADT is a high-level description of a set of operations that can be performed on a particular data structure. It defines what operations are possible on the data structure and what properties these operations should have. An ADT does not specify how the operations are implemented or the internal details of the data structure.

For example, an ADT for a stack would define operations like push, pop, and peek, without specifying whether the stack should be implemented using an array or a linked list.

What is a Data Structure?

A data structure refers to the actual implementation of an ADT using programming constructs like arrays, linked lists, trees, and so on. It defines how the data is stored in memory and how various operations are performed on that data.

In the case of a linked list, it is one of many possible implementations of the ADT called “list.” A linked list consists of nodes where each node contains both data and a reference to the next node in the sequence. This allows for efficient insertion and deletion operations at any position within the list.

Advantages of Using Linked Lists

  • Dynamic Size: Unlike arrays with fixed sizes, linked lists can grow or shrink dynamically as elements are added or removed.
  • Efficient Insertion and Deletion: Linked lists excel at these operations since they only require updating a few references, rather than shifting elements as in arrays.
  • Flexibility: Linked lists can easily accommodate changes in the size and structure of the data.

Disadvantages of Using Linked Lists

  • Random Access: Unlike arrays, linked lists do not provide direct access to elements by index. To access an element, you need to start from the head of the list and traverse it sequentially.
  • Extra Memory: Linked lists require extra memory to store the next node’s reference, resulting in slightly higher memory overhead compared to arrays.
  • Inefficient Search: Searching for an element within a linked list has a time complexity of O(n), as it requires traversing the entire list until the desired element is found.


In summary, a linked list is an ADT that can be implemented using various data structures. It provides dynamic size, efficient insertion and deletion, and flexibility.

However, it lacks random access, requires extra memory, and has inefficient search operations. Understanding the distinction between ADTs and data structures is important for designing efficient algorithms and choosing the right data structure for your specific needs.

If you want to learn more about linked lists or other data structures and ADTs, check out our other tutorials for comprehensive guides!

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