Solutions are mixtures where one substance is evenly distributed in another. The stuff that dissolves is the solute. The stuff it dissolves in is the solvent. When you mix sugar in water, sugar is solute, water is solvent.

Like dissolves like - polar things dissolve in polar solvents, nonpolar in nonpolar. That's why oil and water don't mix.

Concentration Matters

Concentration tells you how much solute is in the solution. Molarity (M) is moles per liter. A 1 M solution has one mole per liter. More moles = higher concentration.