SNAP--> Symmetrical Nonpolar Asymmetrical Polar
Molecular polarity is determined by the shape and distribution of charge in the molecule. To make your life easier, just look the atoms.
If the atoms in the molecule are symmetrical, the charges are balanced by each other. The molecules are considered to be nonpolar.
However, if the molecule is asymmetrical, it is considered to be polar.
So if it is lopsided, it is polar. If it is balanced, it is nonpolar.
Dipole moment is another way of saying the molecule is polar and which side is slightly positive and negative (indicated by the arrow).
***NOTE Water is POLAR, due to an asymmetrical distribution of charge