Gravity is the natural force of celestial bodies, like planets or moons, being attracted to one another. It gives weight to objects, which causes them to fall back to the ground. Gravity is also responsible for many other things such as; keeping the Earth and other planets in orbit around the Sun, the Moon’s orbit around the Earth; our Tides, and maintaining a balance throughout the universe.
Earth’s gravity has a constant - It's an approximate value of 9.81 m/s2, which means that an object falling to the Earth's surface will increase by about 9.8 meters or (32.2 feet) per second - every second. "That's Fast!"
For more information on how Gravity affects things around us and Space check out the following Weather 101's.
Planets in Solar System & The Moon and Tides – Lisa
Various Objects in the Sky & Basic Constellations - Derick