Heron was a Greek mathematician born around 10 AD who worked in applied mathematics and wrote extensively on mathematical and physical subjects. His geometrical works, written in three books, dealt largely with calculating the areas of different shapes, including deriving the famous formula for calculating the area of a triangle based on its three side lengths. This formula, known as Heron's formula, allows calculating the area of a scalene triangle using only the lengths of its three sides. The summary provides the key details that Heron was a Greek mathematician who made important contributions to geometry, in particular deriving the formula for calculating the area of a triangle from its three side lengths.