Stacks are often used in evaluation of arithmetic expressions. An arithmetic expression contains operands & operators. Polish notations are evaluated through stacks. Conversions of different notations (Prefix, Postfix, Infix) in one another are performed by using stacks. Stacks are extensively used inside computer while recursive functions are called. The computers appraise arithmetic expression written into infix notation in two steps. First one, it converts the infix expression to postfix expression & then this evaluates the postfix expression. In each of step, stack is utilized to accomplish the task.