A prime number is a natural number greater than 1 that cannot be formed by multiplying two smaller natural numbers. For example, 5 is a prime number because it cannot be made by multiplying any two smaller natural numbers.
Prime numbers have many important uses in mathematics. They are used in cryptography, number theory, and many areas of science and engineering. Prime numbers were first studied by the ancient Greeks, and they continue to be a subject of fascination for mathematicians today.