PEMDAS is an acronym that helps remember the order of operations in mathematics. It stands for Parentheses, Exponents, Multiplication and Division (from left to right), and Addition and Subtraction (from left to right). This order ensures that calculations are performed correctly and consistently. When solving a mathematical expression, start with any calculations inside Parentheses. Next, evaluate Exponents, followed by Multiplication and Division as they appear from left to right. Finally, perform Addition and Subtraction in the same left-to-right manner. Following PEMDAS helps avoid mistakes in complex calculations.