Why does gravity hold objects on earth?

 
Gravity is an attractive force that works to pull objects together. If 2 objects are close the gravitational pull will be stronger 
Mass and distance determine gravity. The farther two things are away from each other, the weaker the gravitational forces are, the less mass an object has the less gravitational force it exerts

The Sun's gravitational pull keeps our planet orbiting the Sun. The motion of the Moon is affected by the gravity of the Sun AND the Earth. The Moon's gravity pulls on the Earth and makes the tides rise and fall every day. ... The Earth always produces the same acceleration on every object.
Hope this helps have a great day :)