Alkalies are a group of elements, typically including sodium and potassium, that typically have a pH greater than 7 (or are basic in nature). They are found naturally in soil, water, and plants. Alkalies are used in a variety of industrial and household applications, such as detergents, fertilizers, and cleaning products. Many metals are relatively unaffected by alkalies, although some may corrode or corrode more quickly in their presence. The most notable example of this is aluminium, which is very susceptible to corrosion from alkalies. When alkalies are dissolved in water, they form alkali metal ions (such as sodium or potassium). These ions can be detected by measuring the pH of the solution. Alkalies are substances with a pH higher than 7. Examples of alkalies include sodium hydroxide, potassium hydroxide, calcium hydroxide, and potassium carbonate.