In the world of cabling there are two types of cables and they are Copper and Fiber Optics. Some companies chose fiber over copper but those companies have the money to use Fiber Optics and some just go with copper because it is cheaper to use. Each of these two cables has its own strengths and weaknesses.
Copper:
Conductivity and Heat Resistant
Copper wires are second only to silver when it comes to electrical conductivity. Compared with other non-precious metals, copper wires can handle a wider load of electrical power, allowing it to use less insulation and armoring. They have high resistance to heat, eliminating most issues of overloading. Copper wires are also resistant to corrosion. Although patina, a tarnish produced by oxidation, might be present, the material will not lose functionality.
Malleability and Ductility
Copper has a high ductility, allowing wires thinner than human hair strands. Malleability allows it to be bent into nearly any form without the threat of breaking. Copper is used to create thick electrical cable wires within electrical posts and in applications where very thin wires are need, such as in headphone wires.
Small Amounts of Electricity
Although copper wires are excellent conductors, it does not perform very well when handling very exact amounts of small electrical charges. Copper wires are usually not used in high-tech automotive parts and semiconductors because of its inability to control electrical surges. Manufacturers and makers of semiconductors often use silver and gold wires in these applications because these metals are more stable when handling small amounts of electricity, ensuring no electrical surges destroy sensitive components.
Electromagnetic Interference
Copper wire is susceptible to electromagnetic interference, potentially leading to some devices working improperly. Applications that require connection stability, especially in communication, often experience issues when copper wires are used because of this disadvantage. Manufacturers of communication devices prefer using optical fibers, which are unaffected by electromagnetic interference, as opposed to copper wire. (Johnson, 1999-2014)

Fiber: Advantages of fiber optics:
1. Extremely high bandwidth – No other cable-based data transmission medium offers the bandwidth that fiber does.
2. Easy to accommodate increasing bandwidth – Using many of the recent generations of fiber optic cabling, new equipment can be added to the inert fiber cable that can provide vastly expanded capacity over the originally laid fiber. DWDM, or Dense Wavelength Division Multiplexing, lends fiber optic cabling the ability to turn various wavelengths of light traveling down the fiber on and off at will. These two characteristics of fiber cable enable dynamic network bandwidth provisioning to provide for data traffic spikes and lulls.
3. Resistance to electromagnetic interference – Fiber has a very low rate of bit error (10 EXP-13), as a result of fiber being so resistant to electromagnetic interference. Fiber-optic transmission is virtually noise free.
4. Early detection of cable damage and secure transmissions – Fiber provides an extremely secure transmission medium, as there is no way to detect the data being transmitted by “listening in” to the electromagnetic energy “leaking” through the cable, as is possible with traditional, electron-based transmissions. By constantly monitoring an optical network and by carefully measuring the time it takes light to reflect down the fiber, splices in the cable can be easily detected.
Disadvantages of Fiber Optics:
1. Installation costs, while dropping, are still high – Despite the fact that fiber installation costs are dropping by as much as 60% a year, installing fiber optic cabling is still relatively costly. As installation costs decrease, fiber is expanding beyond its original realm and major application in the carrier backbone and is moving into the local loop, and through technologies such as FTTx (Fiber to the Home, Premises, etc.,) and PONs (Passive Optical networks), enabling subscriber and end user broadband access.
2. Special test equipment is often required – The test equipment typically and traditionally used for conventional electron-based networking is of no use in a fiber optic network. Equipment such as an OTDR (Optical Time Domain Reflect meter)
Is required, and expensive, specialized optical test equipment such as optical probes are needed at most fiber endpoints and connection nexuses in order to properly provide testing of optical fiber.
3. Susceptibility to physical damage – Fiber is a small and compact cable, and it is highly susceptible to becoming cut or damaged during installation or construction activities. Because railroads often provide rights-of-way for fiber optic installation, railroad car derailments pose a significant cable damage threat, and these events can disrupt service to large groups of people, as fiber optic cables can provide tremendous data transmission capabilities. Because of this, when fiber optic cabling is chosen as the transmission medium, it is necessary to address restoration, backup and survivability.
4. Wildlife damage to fiber optic cables – Many birds, for example, find the Kevlar reinforcing material of fiber cable jackets particularly appealing as nesting material, so they peck at the fiber cable jackets to utilize bits of that material. Beavers and other rodents use exposed fiber cable to sharpen their teeth and insects such as ants desire the plastic shielding in their diet, so they can often be found nibbling at the fiber optic cabling. Sharks have also been known to damage fiber optic cabling by chomping on it when laid underwater, especially at the repeating points. There is a plant called the Christmas tree plant that treats fiber optic cable as a tree root and wraps itself around the cable so tightly that the light impulses traveling down the fiber are choked off. (Seibert, 2009)

In some situations like wiring up a building you would use copper wire to be able to wire up computers. But in other situations like connecting one country to another you would use fiber optics because the information that you are sending would be able to travel a long distance.
If you wanted to have more information to be sent at a higher rate like sending email to someone in say England . You would have to send the information by Fiber Optics because it is going to go across the ocean. But if you wanted to send an email to someone across the street then you would use a Copper Cable.

Bibliography
Johnson, S. (1999-2014). Copper Wire Advantages & Disadvantages. Retrieved from http://www.ehow.com/info_8152803_copper-wire-advantages-disadvantages.html: http://www.ehow.com
Seibert, P. (2009, June 4). The Advantages and Disadvantages of Fiber Optics. Retrieved from http://hubtechinsider.wordpress.com/2009/06/04/the-advantages-and-disadvantages-of-fiber-optics/: http://hubtechinsider.wordpress.com