A network is a set of devices that exchange data using shared rules. This chapter introduces the core vocabulary — hosts, nodes, links, addresses, protocols — and walks through what physically happens when a single packet crosses the room.
A host is any device that originates or consumes data — a laptop, a phone, a server, a printer, a thermostat. A node is anything that participates in moving data, including hosts plus the devices in the middle (switches, routers, firewalls). A link is the medium between two nodes: a copper cable, a fiber strand, a Wi‑Fi radio channel, a virtual tunnel.
An address is a label that identifies a node so others can talk to it. A protocol is a written agreement about exactly which bits go on the wire, in what order, and what they mean. Networking is, fundamentally, just the disciplined re-application of these five ideas at every layer of the stack.
2 more sections in this chapter, plus a 3-question quiz and a hands-on lab.
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