Solutions; One or more substances are dispersed into another to form a uniform and stable mixture.

Solvent: A substance that can dissolve other substances is called a solvent.

Concentration; The mass fraction of solute in solution is the ratio of solute mass to solution mass.

For example, in a saline solution, the solute is salt, the solution is saline solution, and the solvent is water. Concentration is the percentage of salt mass to solution mass.