Postfix expression:
Postfix notation (also known as Reverse Polish Notation) is a way to represent an expression, where operators follow their corresponding operands. Evaluating an expression represented as postfix notation can easily be done using the stack data structure.
A Stack is a linear data structure that follows the LIFO (Last-In-First-Out) principle. Stack has one end, whereas the Queue has two ends (front and rear). It contains only one pointer top pointer pointing to the topmost element of the stack. Whenever an element is added in the stack, it is added on the top of the stack, and the element can be deleted only from the stack.
Postfix expression: