General relativity is a theory in physics that explains how gravity works. It was developed by Albert Einstein and published in 1915. The theory states that gravity is not a force between two objects, but rather it is a curvature of space-time caused by the presence of mass or energy. This means that massive objects like planets or stars cause the fabric of space to bend around them, which causes other objects to move in curved paths when they are nearby. General relativity has been confirmed through many experiments and observations, including the famous 1919 solar eclipse test, where it predicted the position of a star accurately during an eclipse. It is still widely accepted as one of Einstein's greatest achievements and continues to be studied today in fields such as astrophysics and cosmology.