Vitamins are chemical compounds that are either fat-soluble or water-soluble in nature. Vitamins that dissolve in fat (vitamin A, vitamin D, vitamin E, and vitamin K) tend to accumulate in the body. It is not possible to store water-soluble vitamins (vitamin C and B-complex vitamins, such as vitamin B6, vitamin B12, and folate) since they must dissolve in water before they can be absorbed by the body. The majority of water-soluble vitamins that aren't utilized by the body are excreted through urine.

Vitamins and minerals are combined in multivitamin/mineral supplements. Herbs, for example, are sometimes added to them. Multivitamins, multiples, or simply vitamins are other names for them. When people can't or don't obtain enough vitamins and minerals from diet, multivitamins can help them get the nutrition they need.