The Physical Media
Data needs a physical medium to travel through. The three main types are copper cables, fiber optic cables, and wireless (radio waves). Each has its own advantages and is suited for different situations.
Copper Cables
Copper cables transmit data as electrical signals. They're the most common type of network cable.
Twisted Pair — The most widely used network cable. It consists of pairs of copper wires twisted together to reduce electromagnetic interference. There are two types:
- UTP (Unshielded Twisted Pair) — No additional shielding. Used in most home and office networks. Common categories:
Category │ Speed │ Max Distance │ Use
─────────┼───────────────┼──────────────┼────────────────
Cat 5 │ 100 Mbps │ 100m │ Older networks
Cat 5e │ 1 Gbps │ 100m │ Most home networks
Cat 6 │ 10 Gbps │ 55m (10G) │ Modern offices
Cat 6a │ 10 Gbps │ 100m │ Data centers
Cat 7 │ 10 Gbps │ 100m │ High-performance
Cat 8 │ 25/40 Gbps │ 30m │ Data centers
- STP (Shielded Twisted Pair) — Has extra shielding to reduce interference. Used in industrial environments or areas with high electromagnetic noise.
The connector used is RJ-45 — the familiar rectangular plug you see on Ethernet cables.
Fiber Optic Cables
Fiber optic cables transmit data as pulses of light through thin strands of glass or plastic. They're faster, can travel longer distances, and are immune to electromagnetic interference.
- Single-mode fiber — Uses a single ray of light. Travels long distances (up to 100 km) with high bandwidth. Used by ISPs and long-distance telecommunications.
- Multi-mode fiber — Uses multiple rays of light. Shorter distance (up to 2 km) but cheaper. Used in buildings and campuses.
Fiber is the future of networking. It offers virtually unlimited bandwidth and is immune to the electrical interference that plagues copper cables. The downside is cost — fiber cables and connectors are more expensive than copper.
Wireless
Wireless networking uses radio waves to transmit data. The most common standard is Wi-Fi (IEEE 802.11):
Standard │ Frequency │ Max Speed │ Year
─────────┼────────────┼───────────┼──────
802.11b │ 2.4 GHz │ 11 Mbps │ 1999
802.11g │ 2.4 GHz │ 54 Mbps │ 2003
802.11n │ 2.4/5 GHz │ 600 Mbps │ 2009
802.11ac │ 5 GHz │ 6.9 Gbps │ 2014
802.11ax │ 2.4/5/6 GHz│ 9.6 Gbps │ 2020
Newer standards (Wi-Fi 6 and Wi-Fi 7) offer speeds that rival wired connections, but wireless is still affected by distance, obstacles (walls, floors), and interference from other devices.
Choosing the Right Medium
Copper (Twisted Pair)
+ Cheap, easy to install
+ Widely available
- Limited distance (100m)
- Susceptible to interference
Fiber Optic
+ Very fast, very long distance
+ Immune to interference
- Expensive
- Fragile, harder to install
Wireless
+ No cables needed
+ Mobile devices can connect
- Slower than wired
- Affected by obstacles and interference