What is the Internet?

The Internet is a network of computer networks that are spread throughout the world across individuals, companies, schools, and government agencies.  

A network is a group of computers that are connected for the purposes of sharing information and commonly-used hardware such as printers.

The Internet can:

It is also used to:

When did it start?

The Internet is not as new as you may think!

The Internet can trace its history to the late 1960s when United States Department of Defense (DoD) Advanced Research Projects Agency (ARPA) created a network for sharing information across the country.  The basis of this network was the concept of communications nodes where fault-tolerance enabled the entire network to survive if parts of the entire network were lost. 

The first "Internet", called ARPAnet,  was composed of nodes at UCLA, Stanford, UC Santa Barbara, and University of Utah (1969).  By 1971 there were 15 nodes which increased to nearly 2.2 million nodes by 1990.  The Internet was administratively managed by the National Science Foundation (NSF) from 1990 to 1995 when a number of commercial companies (MCI, Sprint, UUNET Technologies, and others) took over and they have been running it since.

The term Internet actually came from the term "inter-connecting networks" which was shortened to Internet.  You can find a more detailed history of the Internet at the Internet Society web site.

Who is on the Internet?

While the Internet started out as an effort by and for academic and government institutions, its largest growth is with commercial companies and private individuals. 

There are a number of institutions that collect and publish  information on who and what is done on the Internet.  The Georgia Tech Research Corporation Graphic, Visualization, and Usability Center publishes one of these reports.  According to one of their most recent reports published in mid-1998: there has been a significant increase in the number of women on the World Wide Web and that the average income is moving closer to the national average.

Some interesting Internet statistics:

What does the Internet look like?

Clients and Servers

Client computers include desktops, laptops, and other computers that are used for a variety of applications such as word processing, games, and data management.   The server computer is often a more powerful computer with greater processing capability, increased memory, and more data storage space.  The connecting of client and server computers create a network.   Finally, multiple interconnected networks make up the Internet.   

The ability to communicate means that information can be shared between client computers or accessed from the server computer.  In addition, client computers can access programs and functions on the server such as a centralized printer, a central database, or e-mail.

For what it is worth, when you connect a computer from a home to the Internet you are acting as a client to the server at your Internet Service Provider (something we will discuss in a later session).

How do networks (and the Internet) "talk" to each other?

Internet-based networks use a protocol (a special set of instructions) to communicate amongst themselves.  

The protocol is actually a process in which data is changed into electronic signals and back again to facilitate communication between two computers.  For the Internet, this protocol is called TCP/IP (Transmission Control Protocol/Internet Protocol).  TCP/IP works by:

TCP/IP is the basis of a number of functions on the Internet including e-mail, file transfer, and the world wide web.

Names and Addresses

As you can imagine from the last discussion, the key to the Internet is the ability to send packets to destination computers.  This is done via an addressing scheme called IP (Internet Protocol).  The address is defined by a series of four numbers separated by periods (called dots).  A typical address might look like the following:

128.22.182.19

Each set of numbers is limited to 3 digits and equates to the address of a computer on the Internet.

Fortunately, the people accessing the Internet do not have to remember these sets of numbers for everyday use.   Each IP address can be associated to a Fully Qualified Domain Name (FQDN) such as www.domainname.com.  The operation of the  domain name is managed by the server through the Domain Name System (DNS), a program that associates IP addresses to fully qualified domain names.

Domain names are broken up into two main parts:

domain_name.domain_extension

The domain extension identifies the type of organization as follows:

Domain names are assigned by various companies coordinated by the Internic.

What kinds of things can I do on the Internet?

When we think of the Internet we usually think of what we do on the Internet.  We send e-mail, we surf the web, or we download pictures or programs.  The Internet was initially used to provide communications between universities and government agencies using electronic mail or e-mail.  The ability to transmit and receive files soon followed.  

The World Wide Web one of the single greatest reasons the Internet took off in popularity (in addition to the availability of inexpensive computers and cheaper, faster communication).

The concept of services is based on the idea that e-mail, the World Wide Web and other services are based on software programs running on both the client and server computers.  In fact, many of the functions that we use on the Internet are based on protocols including:

Protocols are actually very specific guidelines for enabling computers to communicate and share specific types of data and information.  Protocols are used to define such things as how e-mail and web browsers work.

E-Mail - keeping in touch!!

E-mail was designed to transmit simple text messages between two or more locations.   It has grown in the last few years to include the ability to format the text and append files for transmission.

E-mail addresses are made up of three parts: 

1. userid
2. domain
3. domain extension  

For example dave@dhillman.com (dave is the userid, dhillman is the domain, and com is the domain extension)

E-mail userids are assigned at the server by the e-mail administrator.  When you apply for an e-mail account, you will be assigned a unique userid.

Every e-mail address on the Internet must be unique.  Therefore, the combination of the three segments assures uniqueness.  

For example dave@domain.com is unique from:

E-mail requires the presence of two programs: 

1. a client e-mail program
2. a server e-mail management program 

The server e-mail program operates in a fashion similar to a post office.  When you send e-mail to someone else, you send it first to your server and the server sends it to the final destination.  When you receive e-mail, it is first received by the server and stored in a file (like a post office box) until you request that it be send to your local computer.

The local e-mail computer (client) is used for the following:

There are a number of client e-mail programs that are available for use on computers:

World Wide Web - finding out about the world!!

When many people think of the Internet, they are often referring to the World Wide Web or WWW.  The WWW has gained unprecedented popularity as a resource for information and a means to communicate.  The WWW originated in the early 1990s from work by Tim Berners-Lee and Robert Cailliau, researchers at CERN, the European Laboratory for Particle Physics in Geneva, Switzerland.

The WWW is based on the use of hypertext to link information.  Essentially, a WWW or web document includes text that references other documents which can be located on the same computer or on a remote computer.  In addition to hyperlinks, web documents can also contain images, audio, and video. 

The key to web documents is the use of a web browser.  A web browser is a special software program that reads web documents and presents them to a user.  The browser allows the user to select links and then access the referenced document.

Hyperlinks are constructed using standard Internet features.  A typical web address, called a Uniform Resource Locator (URL), might look like:

http://www.domain.com/pub/docs/ifile.htm

Let's break down this address:

What happens when we surf the WWW?

Other Tools I can use!

There are other Internet tools that are commonly used for uploading and downloading files, managing shared messages, and remote computer access.  The following is a summary of some of these tools:

Keeping Safe on the Net!

There are many things you should be careful about when you are on the Net...

Searching the net...

Finding information on the Internet is easy when you use a search engine.  The following are some of the more popular search engines:

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