Which fundamental force explains why objects have weight?

Weight is not the same as mass; it is the force produced by gravity acting on a mass. On Earth, that force comes from the planet’s gravity and gives objects their downward pull. The distinction matters in orbit, where astronauts still have mass but feel weightless because they are in free fall around Earth. Isaac Newton’s law of universal gravitation first quantified this force, and Einstein later refined our understanding with spacetime curvature.