In physics, weight is the force exerted on an object by the gravitational attraction of a massive body, such as Earth, pulling it toward the body's center.[1] This force is distinct from mass, which measures the object's inertia or amount of matter and remains constant regardless of location; weight, however, varies depending on the strength of the local gravitational field.[2] The magnitude of weight $ W $ for an object of mass $ m $ is given by the formula $ W = mg $, where $ g $ is the acceleration due to gravity, approximately 9.8 m/s² near Earth's surface.[1]Weight is a vector quantity, possessing both magnitude and direction (typically downward toward the gravitational source), and is measured in newtons (N) in the International System of Units (SI), reflecting its nature as a force.[2] In everyday language, "weight" is often misused to refer to mass, leading to confusion; for instance, a person's "weight" is commonly expressed in kilograms, but this actually denotes mass, with true weight being the corresponding gravitational force. For example, a person with a mass of 70 kg has a weight of approximately 686 N on Earth's surface.[1] Weight decreases with increasing distance from the gravitational center—such as at higher altitudes or on other celestial bodies—and becomes zero in free fall or deep space, a condition known as weightlessness, where the object and its surroundings accelerate together under