A solute is the substance that is dissolved in a solvent to form a solution. It is typically present in a smaller amount compared to the solvent. The solute molecules are dispersed throughout the solvent, but they do not significantly change the physical properties of the solvent, such as its boiling point or freezing point. The solute can be a solid, liquid, or gas. Examples of common solutes include salt, sugar, and carbon dioxide.

A residue is the solid substance that is left behind after a separation process, such as evaporation, distillation, or filtration. It is the component that is not volatile (easily evaporated) or that is physically trapped by a filter. The residue is typically collected and can be further processed or analyzed. For example, after evaporating water from a salt solution, the salt would be the residue. After filtration, the solid particles trapped by the filter paper would be the residue.

A saturated solution is a type of solution where the solute has dissolved to the maximum extent possible at a given temperature. This means that adding any more solute will not result in any further solute dissolving; instead, the excess solute will remain undissolved. The concentration of the solute in a saturated solution is at its highest possible value at that specific temperature. The state of the solute (solid, liquid, or gas) does not affect whether a solution is saturated or not.