Bytes
An Abstract Data Type (ADT) describes a data structure from the point of view of the user of that structure.
It defines the operations that are available and how they behave, without saying how they are implemented.
For example, a queue provides operations to add and remove elements following FIFO order.
The same ADT can have different implementations. For example, a queue can be implemented using a linked list or a circular buffer.
The complexity of its operations can change depending on the implementation.