Concentration is the amount of solute dissolved in a given amount of solution. In chemistry, the concentration is generally expressed in units of moles/liter, or more simply molarity (M).

The greater the molarity the greater the concentration and vice versa. For example a 3.4 (M) aqueous solution of lithium bromide (LiBr) would have 3.4 moles of LiBr per liter of solution, while a 1.0 (M) solution would simply have 1.0 mole of LiBr per liter of solution. The 1.0 (M) solution is said to be more dilute, and the 3.4 (M) solution is said to be more concentrated.