The letter "g" represents the acceleration due to gravity, which is approximately 9.81 meters per second squared on the surface of the Earth. This means that an object in free fall will increase its speed by about 9.81 meters per second for every second it falls. Gravity is a fundamental force that pulls objects toward each other, and it is responsible for keeping us grounded on the Earth. Gravity is not only important on Earth but also affects celestial bodies. For example, the Moon orbits the Earth due to the gravitational pull between them. Similarly, the Sun exerts gravitational force on the Earth and other planets, keeping them in their orbits.