Computer networking, like most industries, has its own jargon, which includes technical terms, abbreviations, and acronyms. Without a good grasp of the terminology, it will be difficult to understand the concepts and processes involved in networking. The following list of terms and their definitions is intended to be a quick reference that defines some of the most important words, phrases, and acronyms related to computer networking:

• A network interface card (NIC), pronounced “nick,” is also called the LAN adapter, or just the network interface. This card typically goes into an ISA, PCI, or PCMCIA (PC card) slot in a computer and connects to the network medium. It then connects to other computers through the network media.
• Media refers to the various physical environments through which transmission signals pass. Common network media include twisted-pair, coaxial, and fiber-optic cable, and even the earth’s atmosphere through which wireless transmission occurs.
• A protocol is a set of rules. In the case of a network protocol, it is a set of rules by which computers communicate. The term “protocol suite” describes a set of several protocols that perform different functions related to different aspects of the communication process.
• Cisco IOS software which runs on Cisco equipment and devices, is the industry-leading and most widely deployed network system software. It delivers intelligent network services for enabling the rapid deployment of Internet applications.

Cisco IOS software provides a wide range of functionality, from basic connectivity, security, and network management to technically advanced services. The functionality of Cisco IOS software is the result of a technological evolution. First-generation networking devices could only store and forward data packets.

Today, Cisco IOS software can recognize, classify, and prioritize network traffic, optimize routing, support voice and video applications, and much more. Cisco IOS software runs on most Cisco routers and Cisco switches. These network devices carry most of the Internet traffic today.

• Network operating system (NOS) usually refers to server software such as Windows NT, Windows 2000 Server, Windows Server 2003, Novell NetWare, UNIX, and Linux. The term sometimes refers to the networking components of a client operating system such as Windows 95 or the Macintosh OS.
• Connectivity devices refer to several different device types, all of which are used to connect cable segments, connect two or more smaller networks (or subnets) into a larger network, or divide a large network into smaller ones. The term encompasses repeaters, hubs, switches, bridges, and routers.

The following are three categories of networks:

• A local-area network (LAN) is a network that is confined to a limited geographic area. This area can be a room, a floor, a building, or even an entire campus.
• A metropolitan-area network (MAN) is a network that is larger in size than a LAN and smaller in size than a WAN. This is a network that covers approximately the area of a large city or metropolitan area.
• A wide-area network (WAN) is made up of interconnected LANs. It spans wide geographic areas by using WAN links such as telephone lines or satellite technology to connect computers in different cities, countries, or even different continents.

Network structure is described in the following two ways:

• The logical topology is the path that the signals take from one computer to another. The logical topology may or may not correspond to the physical topology. For instance, a network can be a physical “star,” in which each computer connects to a central hub, but inside the hub the data can travel in a circle, making it a logical “ring.”

The physical topology refers to the layout or physical shape of the network, and includes the topologies in this table.

Bus – Computers arranged so that cabling goes from one to another in a linear fashion

Ring – When there are no clear beginning points or endpoints within a topology, forming a circle.

Star – If the systems “meet in the middle” by connecting to a central hub

Mesh – When multiple redundant connections make pathways to some or all of the endpoints.