The concept of gravity, as defined by Sir Isaac Newton in the 17th century, explains the force that attracts two bodies towards each other. This fundamental force is responsible for keeping planets in orbit around the sun, holding us firmly on the ground, and governing the motion of objects in our everyday lives. Newton's law of universal gravitation states that every mass attracts every other mass, with a strength that increases with mass and decreases with the square of the distance between them. Without this force, our understanding of the universe and the very structure of matter would be profoundly altered.