This document defines and explains different types of real numbers: 1. Natural numbers (counting numbers like 1, 2, 3...) and whole numbers (natural numbers including 0) 2. Integers which include positive and negative whole numbers 3. Rational numbers which can be expressed as fractions like p/q where p and q are integers 4. Irrational numbers which cannot be expressed as fractions and include numbers like π 5. Real numbers which are the sum of all rational and irrational numbers.