Interview Question for Software Engineer at Microsoft:

A stack is an abstract data structure with a philosophy FIFO (First input, first output).
The fundamental methods with this ADT are:
peek(): to get the top of the stack without removing it.
void pop(): to get the top of the stack removing it.
push(void n): to put an element on the top of the stack.
bool empty(): to check if the stack does not have any element.