Copper just above its melting point keeps its pink luster color when enough light outshines the orange incandescence color.
Copper has a reddish, orangish, or brownish color because a thin layer of tarnish (including oxides) gradually forms on its surface when gases (especially oxygen) in the air react with it. But pure copper, when fresh,  is actually a pinkish or peachy metal. Copper, caesium and gold are the only three elemental metals with a natural color other than gray or silver.[ The usual gray color of metals depends on their "electron sea" that is capable of absorbing and re-emitting photons over a wide range of frequencies. Copper has its characteristic color because of its unique band structure. By Madelung's rule the 4s subshell should be filled before electrons are placed in the 3d subshell but copper is an exception to the rule with only one electron in the 4s subshell instead of two. The energy of a photon of blue or violet light is sufficient for a d band electron to absorb it and transition to the half-full s band. Thus the light reflected by copper is missing some blue/violet components and appears red. This phenomenon is shared with gold which has a corresponding 5s/4d structure.[ In its liquefied state, a pure copper surface without ambient light appears somewhat greenish, a characteristic shared with gold. When liquid copper is in bright ambient light, it retains some of its pinkish luster.
Copper is a metal that does not react with water (H2O), but the oxygen of the air will react slowly at room temperature to form a layer of brown-black copper oxide on copper metal.
It is important to note that in contrast to the oxidation of iron by wet air that the layer formed by the reaction of air with copper has a protective effect against further corrosion. On old copper roofs a green layer of copper carbonate, called verdigris, can often be seen. A notable example of this is on the Statue of Liberty.
Copper is malleable and ductile and is a good conductor of both heat and electricity.
The purity of copper is expressed as 4N for 99.99% pure or 7N for 99.99999% pure. The numeral gives the number of nines after the decimal point when expressed as a decimal (e.g. 4N means 0.9999, or 99.99%). Copper is often too soft for its applications, so it is incorporated in numerous alloys. For example, brass is a copper-zinc alloy, and bronze is a copper-tin alloy.
It is used extensively, in products such as:

Electrical applications

1. Copper wire.
2. Oxygen-free copper.
3. Electromagnets.
4. Printed circuit boards.
Lead free solder, alloyed with tin.
5. Electrical machines, especially electromagnetic motors, generators and transformers.
6. Electrical relays, electrical busbars and electrical switches.
7. Vacuum tubes, cathode ray tubes, and the magnetrons in microwave ovens.
8. Wave guides for microwave radiation.
9. Integrated circuits, increasingly replacing aluminium because of its superior electrical conductivity.
10. As a material in the manufacture of computer heat sinks, as a result of its superior heat dissipation capacity to aluminium.

Architecture / Industry

1. Copper has been used as water-proof roofing material since ancient times, giving many old buildings their greenish roofs and domes. Initially copper oxide forms, replaced by cuprous and cupric sulfide, and finally by copper carbonate. The final carbonate patina is highly resistant to corrosion.
2. Statuary: The Statue of Liberty, for example, contains 179,220 pounds (81.3 tonnes) of copper.
3. Alloyed with nickel, e.g. cupronickel and Monel, used as corrosive resistant materials in shipbuilding.
4. Watt's steam engine firebox due to superior heat dissipation.
5. Copper nails were used in making oast cowls.
6. Copper compounds in liquid form are used as a wood preservative, particularly in treating original portion of structures during restoration of damage due to dry rot.
7. Copper wires may be placed over non-conductive roofing materials to discourage the growth of moss. (Zinc may also be used for this purpose.).

Old copper utensils in a Jerusalem restaurant

Household products

1. Copper plumbing fittings and compression tubes.
2. Doorknobs and other fixtures in houses.
3. Roofing, guttering, and rainspouts on buildings.
4. In cookware, such as frying pans.
5. Some older flatware: (knives, forks, spoons) contains some copper if made from Electroplated Nickel silver (EPNS).
6. Sterling silver, if it is to be used in dinnerware, must contain a few percent copper.
7. Copper water heating cylinders .
8. Copper Range Hoods .
9. Copper Bath Tubs .
10. Copper Counters .
11. Copper Sinks .
12. Copper slug tape.

Coinage

1. As a component of coins, often as cupronickel alloy, or some form of brass or bronze.
2. Coins in the following countries all contain copper: European Union (Euro), United States, United Kingdom (sterling),[  Australia and New Zealand.
3. U.S. Nickels are 75.0% copper by weight and only 25.0% nickel.

Biomedical applications

1. As a biostatic surface in hospitals, and to line parts of ships to protect against barnacles and mussels, originally used pure, but superseded by Muntz metal. Bacteria will not grow on a copper surface because it is biostatic. Copper doorknobs are used by hospitals to reduce the transfer of disease, and Legionnaires' disease is suppressed by copper tubing in air-conditioning systems.
2. Copper(II) sulfate is used as a fungicide and as algae control in domestic lakes and ponds. It is used in gardening powders and sprays to kill mildew.
3. Copper-62-PTSM, a complex containing radioactive copper-62, is used as a Positron emission tomography radiotracer for heart blood flow measurements.
4. Copper-64 can be used as a positron emission tomography radiotracer for medical imaging. When complexed with a chelate it can be used to treat cancer through radiation therapy.

Chemical applications

1. Compounds, such as Fehling's solution, have applications in chemistry.
2. As a component in ceramic glazes, and to colour glass.

Other

1. Musical instruments, especially brass instruments and timpani.
2. Class D Fire Extinguisher, used in powder form to extinguish lithium fires by covering the burning metal and performing similar to a heat sink.
3. Textile fibers to create antimicrobial protective fabrics.
Weaponry:
1. Small arms ammunition commonly uses copper as a jacketing material around the bullet core.
2. Copper is also commonly used as a case material, in the form of brass.
3. Copper is used as a liner in shaped-charge armour-piercing warheads.
4. Copper is frequently used in electroplating, usually as a base for other metals such as Nickel.