Gravity is so important because it keeps the Earth in orbit around the sun, keeps water on the earth, prevents us from floating out into space, prevents things in our daily lives from floating around, and many more good things! You can find more information here: http://ellerbruch.nmu.edu/classes/cs255f...

Because without gravity we would all just float off of the Earth and die. I know it sounds a little dramatic, but that's just the way it is!