Sugar water is an example of a solid-liquid solution. Sugar, a solid, is the solute; water, a liquid, is the solvent. Dissolving the solid in the liquid creates the solution.
Sugar dissolves in water because sugar and water molecules have a similar molecular property: they are both polar. To form a solution, the solute and solvent must have similar polarity. In some circumstances, it is also possible to create a solution from a liquid solute and a solid solvent. One example of a liquid dissolved into a solid is dental amalgam. Dissolving mercury, which is liquid at room temperature, into silver forms this type of amalgam.