A solvent is a component in a solution that dissolves the solute, which is another component of the solution. The solvent is generally the component present in the largest amounts in the solution, according to World of Molecules.
The basic chemistry rule regarding solvents is that "like dissolves like." For example, water, being a solvent composed of polar molecules, dissolves salt, which is itself composed of polar molecules. Gasoline, a solvent composed of non-polar molecules, dissolves wax, which is also composed of non-polar molecules. Other well-known solvents include benzene, tetrachloroethylene and turpentine. When two substances are unlike, as with oil and vinegar, one does not dissolve into the other; instead, the substances separate, maintaining their own identities.