Aluminum (British - Aluminium) is a metallic chemical element (atomic number 13). As a light, relatively inexpensive, corrosive resistant metal, it is used in several applications from soda cans to aeronautics. Although it is common in the earth's crust, it was once very expensive to refine and was more valuable than gold. However, a process using electricity allowed it to be easily extracted from its ores and allowed it to be used for more practical purposes.
Although aluminum is highly reactive and is never found in its metallic state in nature, once refined, it quicky combines with oxygen and forms a layer of oxide that resists further corrosion.
The biological role of aluminum is poorly understood. It is clearly not required for any biological processes in either plants or animals (even though many metals are), but is also of very low toxicity (unlike most metals with no biological role). It is easily processed by the kidneys and is passed in urine. However, there is a concern that aluminum may have an adverse effect on persons with poor kidney function. Very high concentrations can result in nerve damage.
Aluminum compounds are used in some antacids, and other compounds are the primary active ingredient in anti-perspirants.