# 6.1: Chapter Introduction

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Learning Objectives

Upon successful completion of this chapter, you will be able to:

• Outline the major components of a data communication system;
• Identify the different types of networks;
• Define the key concepts associated with networking technologies;
• Explain the makeup of the Internet and World Wide Web;
• Describe organizational networking; and
• Summarize widely used web applications for business activities.

# Introduction

In the early days of computing, computers were seen as devices for making calculations, storing data, and automating business processes. However, as the devices evolved, it became apparent that many of the functions of telecommunications could be integrated into the computer. During the 1980s, many organizations began combining their once-separate telecommunications and information-systems departments into an information technology, or IT, department. This ability for computers to communicate with one another and, maybe more importantly, to facilitate communication between individuals and groups, has been an important factor in the growth of computing over the past several decades.

Computer networking really began in the 1960s with the birth of the Internet, as we’ll see below. However, while the Internet and web were evolving, corporate networking was also taking shape in the form of local area networks and client-server computing. In the 1990s, when the Internet came of age, Internet technologies began to pervade all areas of the organization. Now, with the Internet a global phenomenon, it would be unthinkable to have a computer that did not include communications capabilities. This chapter will review the different technologies that have been put in place to enable this communications revolution.

Sidebar: An Internet Vocabulary Lesson

Networking communication is full of some very technical concepts based on some simple principles. Learn the terms below and you’ll be able to hold your own in a conversation about the Internet.

• Packet: The fundamental unit of data transmitted over the Internet. When a device intends to send a message to another device (for example, your PC sends a request to YouTube to open a video), it breaks the message down into smaller pieces, called packets. Each packet has the sender’s address, the destination address, a sequence number, and a piece of the overall message to be sent.
• Hub: A simple network device that connects other devices to the network and sends packets to all the devices connected to it.
• Bridge: A network device that connects two networks together and only allows packets through that are needed.
• Switch: A network device that connects multiple devices together and filters packets based on their destination within the connected devices.
• Router: A device that receives and analyzes packets and then routes them towards their destination. In some cases, a router will send a packet to another router; in other cases, it will send it directly to its destination.
• IP Address: Every device that communicates on the Internet, whether it be a personal computer, a tablet, a smartphone, or anything else, is assigned a unique identifying number called an IP (Internet Protocol) address. Historically, the IP-address standard used has been IPv4 (version 4), which has the format of four numbers between 0 and 255 separated by a period. For example, the domain Saylor.org has the IP address of 107.23.196.166. The IPv4 standard has a limit of 4,294,967,296 possible addresses. As the use of the Internet has proliferated, the number of IP addresses needed has grown to the point where the use of IPv4 addresses will be exhausted. This has led to the new IPv6 standard, which is currently being phased in. The IPv6 standard is formatted as eight groups of four hexadecimal digits, such as 2001:0db8:85a3:0042:1000:8a2e:0370:7334. The IPv6 standard has a limit of 3.4×1038 possible addresses. For more detail about the new IPv6 standard, see this Wikipedia article.
• Domain name: If you had to try to remember the IP address of every web server you wanted to access, the Internet would not be nearly as easy to use. A domain name is a human-friendly name for a device on the Internet. These names generally consist of a descriptive text followed by the top-level domain (TLD). For example, Wikepedia’s domain name is wikipedia.org; wikipedia describes the organization and .org is the top-level domain. In this case, the .org TLD is designed for nonprofit organizations. Other well-known TLDs include .com, .net, and .gov. For a complete list and description of domain names, see this Wikipedia article.
• DNS: DNS stands for “domain name system,” which acts as the directory on the Internet. When a request to access a device with a domain name is given, a DNS server is queried. It returns the IP address of the device requested, allowing for proper routing.
• Packet-switching: When a packet is sent from one device out over the Internet, it does not follow a straight path to its destination. Instead, it is passed from one router to another across the Internet until it is reaches its destination. In fact, sometimes two packets from the same message will take different routes! Sometimes, packets will arrive at their destination out of order. When this happens, the receiving device restores them to their proper order. For more details on packet-switching, see this interactive web page.
• Protocol: In computer networking, a protocol is the set of rules that allow two (or more) devices to exchange information back and forth across the network.

This page titled 6.1: Chapter Introduction is shared under a CC BY-SA license and was authored, remixed, and/or curated by David T. Bourgeois (Saylor Foundation) .