Polarity is the degree of charge separation in molecules

Polarity is the degree of charge separation in molecules. Polar molecules always have an excess of electrons on one end whereas non-polar molecules have a more symmetrical charge distribution.

Polarity affects interactions between molecules. Depending on whether the participating molecules are polar or non-polar guides the way they interact with each other.

Polar molecules interact with each other by strong attractive whether polar molecules interact with non-polar molecules through dipole- induced dipole interactions ( a weak dipole induced subject to charge of a dipole similar to the way a permanent magnet induces a temporary magnetism on a metal ).

Polar molecules mix easily with another polar molecule and form a homogenous phase / solution whether when they are subjected to mix with a non-polar molecule they stay as separate phases and don't dissolve into each other. This gives rise to the term "like dissolves like".