Network

Eternet

IEEE 802.3 standard
speed: 1 Gbps standard; 2.5 Gbps commonly available; 10 Gbps costs more, uses more power; higher speeds are available, best suited to racks of equipment
transceivers: transmit and receive ethernet signals over long distance physical media; can be built into motherboards and network interface cards; can be interchangeable modules, SFP+ is common
twisted-pair (copper) cables: CAT5e up to 100 m at 2.5 Gbps; CAT6 up to 55 m at 10 Gbps; CAT6a up to 100 m at 10 Gbps; CAT8 up to 100 m at 40 Gbps
optical cables: support greater speeds and distances than twisted pair but cost more; many standards for data rate and length
twinax cables (coaxial copper): direct attach SFP+ cables for short distances; transceivers not required; cost more than twisted pair

IEEE 802.11 standard
speed: Wi-Fi 4 (802.11n) up to 600 Mbps; Wi-Fi 5 (802.11ac) up to 6 Gbps; Wi-Fi 6 (802.11ax) up to 9 Gbps; Wi-Fi 7 (802.11be) up to 23 Gbps; actual speeds reduced by overhead, distance, and imperfect conditions
security: WPA3 (2018) provides better security than older WPA2, WPA, and WEP; security can be improved by separating wireless traffic with a firewall or router

connects devices together into a network: OSI layer 2 (data link); transmits all network frames on all interfaces; usually internal, used to connect different media types

connects devices together into a network: OSI layer 2 (data link); remembers which MAC address is connected to which interface; forwards network frames by MAC address to avoid collisions; spanning tree protocol prevents loops; may be managed (VLAN, etc) or unmanaged

connects networks together: OSI Layer 3 (network); communicates with adjacent routers; forwards network packets by IP address to appropriate interface; may include switch hardware

filters network packets: OSI Layers 4 and above (transport, application); forwards or drops network packets according to transport and application data; includes router funcion; may include switch hardware

drivers: most UNIX versions support a limited number of devices
router and firewall software: often implemented in UNIX with tools like pf (BSD) and netfilter (Linux); unneeded UNIX features are often removed for better performance, reliability, and security; user interface often is provided by a web server
router and firewall hardware: multiport NICs are available for general-purpose computers; dedicated hardware can be smaller, faster, more reliable, less expensive, and use less energy