What does polar and non polar mean?

Polar is the separation of electric charge leading to a molecule or its chemical groups having an electric dipole or multipole moment.

Non-polar is one in which the electrons are distributed more symmetrically and thus does not have an abundance of charges at the opposite sides.

This means that in a polar bond, the electronegativity of the atoms will be different. For nonpolar bonds the electronegativity of the atoms will be equal. In a polar bond you will have an unequal sharing of electron pairs which causes a molecular dipole. Bonds will cancel or not depending on the shape of the molecule. 

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