A stack is an abstract data type defined as a list or collection carrying the restriction that insertion and deletion may be performed only at one designated end, called the top, which yields last-in-first-out (LIFO) ordering. As an ADT it is specified purely as a logical or mathematical model by its operation interface — push, pop, top, and isEmpty — all required to run in constant time O(1), with implementation deliberately left unspecified. The concept sits in data structures within computer science, alongside arrays and linked lists, and serves as the abstraction underlying call-stack execution, recursion, undo histories, and balanced-delimiter checking.
A stack is an abstract data type defined as a list or collection carrying the restriction that insertion and deletion may be performed only at one designated end, called the top, which yields last-in…