Not only does the earth create a gravitational field around it, the other bodies in the universe each create their own field.

  In our daily lives we can directly see the effect of the gravitational force of the moon and the sun in the tides.

  The force of the tides is what we call the difference between the gravitational intensity created by a heavenly body on the surface and in the centre of another one.  

The difference in the gravity created by the moon on the surface A and in the centre B of the earth is the lunar tide, which is responsible for the variations in the level of our seas.