Network

Hub: All incoming traffic is replicated out onto all ports (Layer 1 – Physical)
Bridge: Connects 2 physical segments together (Layer 2 – Data Link)
Switch: LAN – physical connection of network segments. Sends traffic based on MAC Address (Layer 3 – Network)
Router: Connects networks together and determines route to take. Send traffic based on IP addresses. (Layer 3 – Network)
Subnet Mask: Specifies which part of a given IP address is the network address and which part is the computer on that network’s.
i.e. given Subnet Mask: 255.255.0.0 and IP address of 192.168.1.4
In the Subnet Mask the non zero represents the parts of the IP that belong to the network, in this case it will be 192.168 the .1.4 is the machine/device in that network.
PAN: Personal Area Network. Bluetooth, Zigbee, NFC and RFID all fall under the PAN domain.
Zigbee: Low power, low bandwidth PAN technology. Leverages use of mesh networking due to its limited range. Uses in light bulbs, locks, HVAC, medical devices, etc..
NFC: Near Field Communications PAN technology. Mean to be a closed proximity technology with a limited range of 1-2 inches. Subset of RFID. Uses are contact less smart phone payments, authentication(badges), credit card payments, transit passes. Security is not mandated.
RFID: Radio Frequency Identification: Use to identify objects and tracking location, PAN technology. Typically used with an RFID tag and and RFID reader. RFID tags can be significantly small. Can operate at great distance.
5G: Digital cellular network with speeds of 1-2 gigabit. Features low latency, high bandwidth and high density support.