Water is a versatile solvent because it dissolves more substances than any other liquid. As a polar molecule, with the oxygen side having a negative charge and the hydrogen side having a positive charge, water can bind to ions and other polar molecules, dissolving them.
The majority of polar substances placed in water are dissolved. For example, water and sodium chloride, or table salt, interact so strongly that water breaks apart the ionic forces that keep the sodium and chlorine together. Each atom of chlorine is attracted to hydrogen, and each atom of sodium is attracted to oxygen.
Although water is often referred to as the "universal solvent," there are many substances that water cannot dissolve. Non-polar liquids, such as oils, cannot be dissolved in water, as water molecules are attracted to other water molecules more strongly than to oil. This results in a clearly defined separation between still water and oil molecules, where the less dense oil sits on top of the more dense water. Non-polar plastics do not dissolve in water for the same reason, which has resulted in large concentrations of plastic materials like shopping bags, cups, gasoline cans and bottles in the world's oceans and waterways.