What is Gravity
All objects have a force that attracts them towards each other. This force is called gravity. Even you, attract other objects to you because of gravity, but you have too little mass for the force
to be very strong.
Gravitational force increases when the masses are bigger and closer. This means that the gravitational force on Moon is less than on earth, because Moon has less mass than Earth.
Good examples of very massive objects that possess gravitational force include the moon and other planets. Consider the earth on which humans live. Everything tends to fall on the ground and stays there. If you jump, you came down again. Throw a ball upwards, and it will surely come down.
"Down" is towards the centre of the Earth, wherever you are on the planet.
This is a result of gravitational force, which pulls objects towards the center of the earth.