Introduction to the Internet

  1. The Internet
  2. The Internet vs. the Web
  3. A Brief History of the Internet
  4. Sending Data with TCP/IP
  5. Identifying Computers with IP Addresses
  6. DNS: Names are Easier than Numbers
  7. URLs: Where Exactly Do You Want to Go?
  8. Intranets on the Internet
  9. References & Further Reading

The Internet

The Internet is a vast, electronic network connecting many millions of computers from every corner of the world. The Internet is a publicly-accessible network that "consists of millions of smaller domestic, academic, business, and government networks" (Wikipedia: Internet, July 2007).

A computer connected to the Internet is commonly referred to as a host. Connections are made using telephone lines, cable data lines, fiber-optic, or even wireless signals. This connected-ness allows computers to send and receive information in the form of digitized data on demand. The data is passed back and forth between host computers using packets and protocols, such as electronic mail (e-mail) for messaging, file transfer protocol (FTP) for moving files, telnet for accessing information, hypertext transfer protocol (HTTP) for serving up Web sites, custom protocols, etc. Other common services of the Internet include the World Wide Web (WWW), Voice Over IP (VoIP), Instant Messaging (IM), streaming media, etc.

The Internet itself is decentralized---no one entity is completely responsible or has total control; however, your connection to the Internet is probably controlled by an Internet Service Provider (ISP).

When your computer is connected to the Internet you are online. Nowadays one typically has to plug-in to a network outlet, or select an active wireless signal, or dial into a service provider using a modem to get online. Sometimes one must authenticate one's computer with the controlling ISP in order to gain connectivity.

Internet Map
"Visualization of the various routes through a portion of the Internet." - Matt Britt, Wikipedia.
Available: http://en.wikipedia.org/wiki/Image:Internet_map_1024.jpg

The Internet vs. the Web

The Internet is not the same as the World Wide Web (WWW or just the Web), though this is a common and understandable misperception. The World Wide Web consists of all the Web sites and pages served on the Internet via HTTP. In addition to the fact that Web pages are served by HTTP, a central identifying feature of Web pages is their use of hyperlinks, which allow a user to quickly move from one web page to another, even if the pages are on different servers in different parts of the world! Though the Web relies on the Internet to connect your web browser to different web servers, the Web is just a part of a number of systems that make up the Internet

A Brief History of the Internet

The Internet began as ARPANET back in 1969. ARPANET was a large wide-area network created by the United States Department of Defense Advanced Research Project Agency (ARPA). It served as a testbed for new networking technologies. It linked many universities and research centers. The intention here was to ensure that the transfer of information between servers was possible if there was a nuclear attack. The first two nodes that formed the ARPANET were UCLA and the Stanford Research Institute. The third followed shortly thereafter and was established right here in our own back yard at the University of Utah.

Sending Data with TCP/IP

Protocols are pre-established means of communication. It is just a fancy nerdy way of saying that there is an agreed-upon format for transmitting data between two devices. TCP/IP stands for Transmission Control Protocol/Internet Protocol and is the basic communication language or protocol of the Internet. It can also be used as a communications protocol in a private network. When you are set up with direct access to the Internet, your computer is provided with a copy of the TCP/IP program just as every other computer that you may send messages to or get information from also has a copy of TCP/IP.

The term TCP/IP actually refers to a whole family of protocols, of which TCP and IP are just two. The key here is to understand what each does. TCP is the protocol that establishes a virtual connection between a destination and a source. TCP guarantees delivery of data and also guarantees that packets will be delivered in the same order in which they were sent. IP is the protocol that is responsible for packaging the little packets of information and delivering them.

TCP/IP uses the client/server model of communication in which a computer user (a client) requests and is provided a service (such as sending a Web page) by another computer (a server) in the network.

The TCP/IP family of protocols are open protocols, meaning they are not proprietary or for-profit.

Identifying Computers with IP Addresses

In order for host computers to share information there needs to be a way to identify each computer. This is where the IP address comes in. IP stands for Internet Protocol and is metaphorically the postal address of your machine, identifying its location on the Internet. An IP address looks something like this: 199.199.254.254. The problem is that people have a hard time remembering an IP address, so along came Domain Name Services to make it easier on us.

DNS: Names are Easier than Numbers

Domain Name Services (DNS) attach text to our numeric IP addresses, allowing users to use the DNS as a proxy for the IP address. While IP addresses are often provided by your ISP, one must register a domain name for a cost through a DNS hosting service. DNS host servers then are used to convert our text DNS address to its digital IP address equivalent.

For example:

URLs: Where Exactly Do You Want to Go?

Universal Resource Locators, otherwise known as URL's, are a more precise way of identifying information on a server. Whereas a DNS simply specifies the general domain name of a server, a URL gives the protocol, the domain, the directory, and even the file. To continue the address metaphor, while a DNS will drop you off at a given location--typically putting you at the front door--a URL will send you to the domain and (if necessary) through the front door, into the room you want to be in, and right onto the chair you want to sit in.

A URL consists of the following parts:

  1. protocol (such as http:// or ftp://)
  2. host name (the Web server's IP address or domain name)
  3. directory (i.e. folder)
  4. file name
url diagram

Intranets on the Internet

Though the name might be confusingly similar to Internet, an Intranet is a subsystem that takes advantage of the larger Internet. An Intranet is a closed network that typically belongs to a specific organization and is accessible only to members of that organization as regulated via some security method.

For example, if you were in employee at Novell you would have access to their Intranet, which is dubbed the Innerweb. Novell's Innerweb is a huge collection of web pages from each department. Using the Novell Intranet you could, for example, order food for a meeting from the catering department or request a purchase order from the purchasing department using an online form. How about getting some deals on tickets to local events or places like Lagoon? You can do that too. Only Novell's employees have access to Innerweb--Novell's company Intranet.