In a solution, the solute is the substance that is dissolved. The solvent is the substance that does the dissolving. Saltwater is a solution of salt in water. Salt is the solute. Water is the solvent. The solute is usually present in a smaller amount than the solvent. When you add sugar to coffee, sugar is the solute. The coffee is the solvent. The distinction matters for calculating concentration and predicting properties.

Solutes can be solids, liquids, or gases. Salt and sugar are solid solutes. Ethanol in water is a liquid solute. Carbon dioxide in soda is a gas solute. The solute particles are dispersed throughout the solvent. In a solution, the solute and solvent form a homogeneous mixture. The solute particles are too small to see and do not settle out.

The properties of a solution depend on the solute and the solvent. Adding solute affects boiling point, freezing point, vapor pressure, and osmotic pressure. These are called colligative properties. They depend on the number of solute particles, not their identity. That is why salt melts ice and antifreeze lowers the freezing point of water.

Solutes can be electrolytes or nonelectrolytes. Electrolytes dissociate into ions in solution and conduct electricity. Sodium chloride is a strong electrolyte. Acetic acid is a weak electrolyte. Sugar is a nonelectrolyte. The distinction affects the colligative properties and the behavior of the solution.