Media is what data travels through. There are three main types of media: Copper, Fiber (glass), and Air.
Copper: Signal can travel 300 meters unrepeated.
Fiber: Signal can travel 3000 meters unrepeated in single mode, 2000 meters unrepeated in multi mode.
Air- Signal can travel 300 meters unrepeated.
Repeater- Retimes and regenerates networks signals
Hub- multi-port repeater, huge collision domain
Collision Domain- Area where collisions occur
Bridge- Filters traffic based on physical addresses (MAC addresses)
Switch- multi-port bridge with lots of collision domains
Micro Segmentation- Create a lot of collision domains
Router- routes data packets based on IP address
IP- Internet Protocol Address
NIC- Network Interface Card. This gives you your digital "fingerprint"
Switches are much better than repeaters, hubs, and bridges. They do everything the first three do, except with less problems. Since they have a lot of small collision domains instead of one huge one (like a hub), there is less chance a collision will occur.