Real numbers are a set of numbers that include all the rational and irrational numbers. Rational numbers can be expressed as fractions, such as 1/2 or 3, while irrational numbers cannot be written as simple fractions, like π or the square root of 2. Together, they form a continuous number line that extends infinitely in both positive and negative directions. Real numbers are used in everyday life for counting, measuring, and performing calculations. They can represent quantities such as distance, temperature, and time. The concept of real numbers is fundamental in mathematics and is essential for various fields, including science, engineering, and finance.