Postfix Notation, also known as Reverse Polish Notation (RPN), is a mathematical notation in which operators follow their operands. For example, instead of writing "3 + 4", you would write "3 4 +". This eliminates the need for parentheses to indicate the order of operations, making it easier to evaluate expressions in a straightforward manner. In Postfix Notation, expressions are evaluated from left to right using a stack data structure. When an operand is encountered, it is pushed onto the stack, and when an operator is encountered, the required number of operands is popped from the stack, the operation is performed, and the result is pushed back onto the stack.