Copper

Copper wires are the most common network cabling media in homes and offices
Twisted-Pair cables are either Shielded (STP) or Unshielded (UTP)
- Copper Shielded Twisted Pair (STP) cables reduce noise and Interference by insulating the twisted-pair wires.
- Copper Unshielded Twisted Pair (UTP) are cheaper than STP cables, but are more prone to interference
STP and UTP cables can support PoE, reducing wiring overhead for hard-to-reach places.
Copper cables are frequently terminated with a Registered Jack 45 (RJ45)^[1] plug
- These cables can by wired as straight through or crossover^[2]
  - Straight through cables
    - Wired the same on both sides
      - i.e., orange-stripe on 1, solid orange on 2, etc.
    - Used to connect devices of different types together
      - e.g., a router and a computer
  - Crossover cables
    - Each side of the cable is wired a little differently
      - i.e., the orange and green twisted pairs flip on each side of the cable
    - Used to connected two devices of the same type
      - e.g. two computers, two switches, etc.
- Auto-MDIX is configured on most modern networking equipment to allow network administrators to use either straight through or crossover cables without issue

There are 4 wire pairs in a UTP cable, with each cable in a colored pair either solid or striped
- Orange
- Blue
- Green
- Brown
In traditional Ethernet (10BASE-T and 100BASE-TX, or Ethernet and Fast Ethernet), only TWO out of the four available pairs are used for data transfer
In 1000BASE-T (Gigabit) and above, all 4 pairs are used

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