Long before it was isolated as a pure metal, aluminum was used in the form of ionic salts as early as ancient Greek and Roman times. Aluminum salts like alum (potassium aluminum sulfate) are highly hygroscopic and are used as desiccants and astringents. These salts were obtained from minerals in mined rocks.
Aluminum is actually quite abundant in the Earth's crust as various salts and minerals. The pure metal, however, is rarely found in nature. The metal was first chemically made in the early 1800's and is credited to chemist Friederich Wohler. Aluminum is extremely difficult to isolate from its natural alloy bauxite, so it is produced from natural aluminum salts via electrochemistry. Prior to an industrial process to produce aluminum, the pure metal used to be as valuable as gold.
In 1886, the Hall-Heroult process was discovered independently by two different men in the US and Europe. It is an electrochemical way to produce aluminum metal from passing an electric current through molten alumina (Al2O3). This is still the preferred method for aluminum production. Due to its light weight and strength, it is in demand for building things such as airplane bodies.
As an aside, the IUPAC (a major international chemistry organization) actually prefers the spelling of the word as "aluminium," but it also recognizes the spelling "aluminum" (the preferred spelling in North America) as equally correct.