According to Einstein, gravity is not a pulling forced but a curvature in spacetime.
For example:-
Consider earth, when it occupies a particular place in space it forms a curvature around it like when a boat displays a particular amount of water below it when it floats.
Or when you sit in a bed, the bed gives way to accommodate you and a little of the area around the bed gives way to accommodate you too.
So according to Einstein each object in space bends a particular amount of space towards it and bigger the object bigger the space, and black hole have infinte gravity.
This explains as to why each object rotates around a particular orbit around other objects like when the moon rotates around the earth, earth rotates around the sun.
This principle has been used to launch satellites in to space.
