What is gravity?

Every object with mass attracts every other object — that is gravity. Isaac Newton first described it mathematically in 1687, showing the same force that drops an apple keeps the Moon in orbit. In 1915, Albert Einstein reframed gravity in his general theory of relativity: massive objects warp the fabric of spacetime, and other objects simply follow the curves. On Earth, gravity accelerates falling objects at about 9.8 meters per second squared. It is by far the weakest of the four fundamental forces, yet because it acts across vast distances it shapes the orbits of planets and the structure of galaxies.