Polarity refers to the distribution of electrical charge within a molecule, which can create regions of positive and negative charge. This uneven distribution affects how molecules interact with each other, influencing properties like solubility and boiling points. For example, water (H2O) is a polar molecule, meaning it has a positive end and a negative end, allowing it to dissolve many substances. In contrast, nonpolar molecules have an even distribution of charge, resulting in no distinct positive or negative regions. This difference is crucial in chemistry, as it determines how substances mix or react. For instance, oil is nonpolar and does not mix well with water due to their differing polarities.