A solution is a homogeneous mixture composed of two or more substances, where one substance (the solute) is dissolved in another (the solvent). In a solution, the solute particles are evenly distributed throughout the solvent, resulting in a consistent composition. Solutions can exist in various states, including liquids (like saltwater), gases (like air), and solids (like alloys). Their properties can vary based on the concentration and nature of the solute and solvent.