A real number is any value that can be found on the number line. This includes both rational numbers, which can be expressed as a fraction (like 1/2 or 3), and irrational numbers, which cannot be expressed as a simple fraction (like π or the square root of 2). Real numbers can be positive, negative, or zero. Real numbers are used in various fields, including mathematics, physics, and engineering, to represent quantities and measurements. They are essential for calculations involving distance, time, and other continuous values. The set of real numbers is often denoted by the symbol ℝ.