Which two factors are essential for a molecule to be considered polar?

They should have a positive difference in Electronegativites, & both are partially charged. Some negative & positive are both the elements, instantaneous dipoles form,  form to "London dispersion forces". So it to be polar, the compound must also be unsymmetrical, & the shared to unshared ratio must fit the equation X:0, x amount of shared to 0 unshared.