What types of network media are used to connect devices, and what factors affect media selection?

Twisted-pair copper, fiber-optic, coaxial, and wireless; choose based on distance, environment, required data rate, and cost.

"Media" is simply the physical path a signal travels between devices, and each type carries the signal differently — which is why no single one is best for every situation.

Types of network media:

• Twisted-pair copper — carries signals as electrical pulses; cheap and easy, the default for LAN connections, but limited in distance (~100 m)
• Fiber-optic — carries signals as pulses of light through glass/plastic; spans long distances at very high speed and ignores electrical interference, but costs more
• Coaxial — copper core with shielding; older technology, still used for some broadband/cable runs
• Wireless — uses radio waves and no cable at all, giving mobility, but is shared, slower, and affected by range and interference

Why you weigh several factors when choosing — the cheapest medium isn't always usable:

• Distance the signal must travel without degrading
• Environment it's installed in (electrical noise, outdoors, etc.)
• Data volume and speed the link must support
• Cost of both the media and the installation

Go deeper:

• Transmission medium (Wikipedia) — how twisted-pair copper, coaxial, fiber-optic and wireless each carry a signal, and their trade-offs.