Copper is probably the first metal to be used by humans for anything other than ornaments and jewelry. Only five metals routinely occur in the metallic form in nature. Copper, gold, and silver all belong to one chemical group of metals that are of low chemical activity, and platinum is the most common element in its group.
Brass is softer and easier for work than bronze, but stronger than copper. It is easily polished and can be used for such decorative purposes as railings and trim. In addition, brass is very useful for valves and connectors. Copper tubing is frequently joined with threaded brass connectors. Brass will easily expand under pressure, making it ideal for compression fittings and for shell casings for ammunition. The development of brass cartridges for ammunition made possible breech loading rifles, revolvers, and automatic weapons.
Brass comes in a variety of formulas, with some types being easily shaped. Other formulas may be suitable for casting. A variety of finished colors are available, and most brass is easy to polish. Indeed, polishing brass is a favorite activity of boat owners, bar keepers, military personnel, and sycophants (as in the HMS Pinafore). Brass rails and fittings are favorites for a variety of architectural use.