Final answer:
The force that every mass exerts on every other mass is called gravity, which is described by Newton's law of gravitation. Gravity is responsible for the attraction between masses and determines the weight of objects, which can vary by location unlike mass.
Step-by-step explanation:
The force that every mass exerts on every other mass is called gravity. According to Newton's law of gravitation, every mass attracts every other mass with a force that is directly proportional to the product of their masses and inversely proportional to the square of the distance between their centers. This gravitational force is what gives us our sense of weight, and it is the reason why objects attract each other in the universe.
Importantly, while mass and weight are sometimes used interchangeably in everyday conversation, they are not the same. Mass is a measure of the amount of matter and is constant regardless of location, whereas weight is the force due to the pull of gravity on that mass and can vary with location. The SI unit of force, including gravitational force, is the newton.