Terminology

protocol

a set of rules governing the operation of some communications function
e.g. IP - rules for routing data
      TCP - rules for reliable, in-sequence delivery of data

protocol data unit (PDU) (a.k.a. packet)

a formatted unit of data that is terminated across a network. The information carried in a PDU is often called its payload.

protocol stack

a layered set of protocols that work together to provide communication between applications
e.g. TCP + IP + Ethernet

protocol suite

a familty of protocols that work together in a consistent fashion
e.g. TCP/IP

host

a computer that runs applications and has one or more users
(a.k.a. station, computer, computer system, PC)
A host that supports TCP/IP can act as an endpoint of communication.

router

a device that routes data through a network
(a.k.a. gateway, but gateways tend to perform some kind of protocol translation)

internet

a set of network facilities connected by routers

Internet

a very special internet, connecting thousands of networks together

network node, network element, system:

a communication entity, but not necessarily a host
e.g. host, router, bridge, gateway, server
The goal of network management is to control and monitor all nodes in a network.

local area network (LAN)

a network covering a small geographical area
e.g. office, lab, campus

wide area network (WAN)

a network covering a large geographical area
e.g. city, state, continent

link

any medium over which nodes can communicate using a link layer protocol
e.g. Ethernet segment, PSTN, satellite, microwave

hacker

someone who has a high degree of computer or network skill
e.g.,  Robert Kahn, Vinton Cerf, Brian Kernighan, Dennis Ritchie, Ken Thompson, Bill Joy, Bjarne Stroustrop, Linus Torvalds, James Gosling, Richard Stallman, et al.

cracker

someone who tries to break into private computer resources

byte

the smallest addressable unit in a computer
For all intents and purposes, a byte is 8 bits in length (a.k.a. octet)

logical byte

an addressable unit other than 8 bits in length

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