This document discusses inequalities and ordering real numbers. It introduces the symbols for less than (<) and greater than (>), and defines them in terms of positive and negative differences between real numbers. Less than or equal to (≤) and greater than or equal to (≥) are also covered. The document explains how to represent intervals and sets of real numbers using inequalities and set notation on a number line. It provides examples of combining inequalities with set operations like union and intersection.