So let's suppose we take water molecules and we place some type of polar substance into the water molecule. For example, sodium chloride. Now, sodium chloride is polar because it consists of an ionic bond. And an ionic bond is basically a bond in which we have an unequal distribution of charge. So one of the atoms, namely the chloride, is more electronegative, so it will have that full negative charge. But the sodium is not very electronegative, and it will give away those electrons, and so it will have a positive charge.