Stack & Queue

• A stack is an abstract data type that serves as a collection of elements, with two main principal operations: Push, which adds an element to the collection, and Pop, which removes the most recently added element that was not yet removed.

• A queue is a collection of entities that are maintained in a sequence and can be modified by the addition of entities at one end of the sequence and the removal of entities from the other end of the sequence.

• Circular queue is a data structure that uses a single as if it were connected end-to-end. This structure lends itself easily to buffering data streams.