Abstract Data Type (ADT)
TL;DR An Abstract Data Type (ADT) defines what a data structure does rather than how it is implemented, separating behavior from implementation.
An Abstract Data Type (ADT) is a fundamental concept in computer science that describes a data structure in terms of its operations and behavior, without specifying how those operations are implemented. By focusing on the actions permitted and the results they produce, ADTs enable programmers to design systems that are modular, flexible, and easier to reason about. This abstraction is especially important in large software systems and AI-related software, where clarity and maintainability matter as much as performance.
An ADT can be thought of as a set of rules for using a system without regard to its internal workings. For example, when you use a list, you know you can add items, remove items, or look something up, but you do not need to see how the list is stored in memory. ADTs make software easier to understand and use by hiding complexity and allowing users to focus on outcomes rather than internal mechanics.
Technically, an ADT is defined by a mathematical model consisting of a set of values and a set of operations on those values. The specification includes operation signatures, constraints, and expected behavior, but omits implementation details such as memory layout or algorithms. Common examples include stacks, queues, lists, sets, and maps, which can be implemented using arrays, linked lists, trees, or hash tables. ADTs support principles like encapsulation and interface-based design, enabling multiple implementations to be swapped without affecting dependent code.
Definition based on behavior, not implementation
Clear separation between interface and internal structure
Support for modular, maintainable software design
Multiple possible implementations for the same ADT
Widely used in algorithms, data structures, and system design
ELI5 An abstract data type is like knowing what buttons a toy has and what they do, without knowing what is inside the toy. You can use it effectively even if you do not understand how it works internally.
