The universal solvent is water. It is composed of two hydrogen atoms and one oxygen atom, making it a polar molecule, meaning it has a positive end and a negative end. This polarity allows water molecules to form hydrogen bonds with other polar molecules, making it an excellent solvent. Additionally, water has a high surface tension, which means it can dissolve both hydrophilic (water-loving) and hydrophobic (water-hating) molecules. This makes it capable of dissolving a wide variety of substances, making it the universal solvent.