When you mix sugar into water and stir until it disappears, you've created a solution: a mixture where one substance dissolves completely and evenly into another. The sugar molecules spread out so thoroughly that you can't see them anymore, but you can taste them in every sip. Salt water, lemonade, and the air we breathe (a mixture of oxygen, nitrogen, and other gases) are all solutions.

Scientists distinguish solutions from other mixtures. In muddy water, you can see dirt particles floating around because they haven't dissolved. That's a suspension, not a solution. But in salt water, the salt has broken apart into invisible pieces spread uniformly throughout: that's a true solution. The substance that dissolves (like sugar) is called the solute, while the substance doing the dissolving (like water) is the solvent.

The word also means the answer to a problem. When you finally figure out a challenging math problem, you've found the solution. When engineers develop a better way to purify drinking water, they've created a solution to an important challenge. In this sense, a solution resolves something that was difficult or unclear. You might work through several attempts before discovering the right solution, just as you might try dissolving different amounts of ingredients before creating the perfect lemonade.