The less than sign, also called the less than symbol, is an inequality symbol that is used to show when a given number or expression represents a smaller quantity than another given number or expression. The less than symbol is one of the most common symbols used in math, so it is important to know the less than meaning behind the symbol. In inequalities, this symbol tells us that the number or expression on the left side of the inequality is smaller than the number or expression on the right side of the inequality.