Introducing the Internet

Source: Learning to Use the Internet

Introducing the Internet

• A Description of the Internet

• Internet Services and Tools

• How the Internet Works

• How the Internet Developed

• Explanation of Internet Domain Names and Addresses

A Description of the Internet

The Internet is:

• millions of people communicating electronically on a one-to-one basis or in groups to share ideas and information.

• a vast collection of information on a wide variety of topics that can be searched and retrieved electronically.

A Description of the Internet (Cont.)

• A network of tens of thousands of computer networks that connect over a million computer systems. These networks communicate by exchanging data according to the same rules, but they may be using different technologies.

Internet Services

• Electronic Mail (e-mail)

• Telnet

• FTP

Electronic mail (e-mail)

• Lets you send and receive messages in electronic form.• These messages can be text, spreadsheets, word-

processing documents, images, programs, etc.• Can join interest or discussion groups and mailing lists.• Example of an e-mail address:

somebody@lib.umich.edu where somebody is the user name, lib.umich.edu is the domain name of the site used.

Telnet

• Allows you to connect and log into a remote computer.

• You can use it to access any of the public services or tools at the remote site.

• Can be used for access to libraries, databases, or other Internet services.

FTP

• File Transfer Protocol

• Lets you transfer files from one computer on the Internet to another.

• Using anonymous FTP one can retrieve files without being a registered user on another computer system.

Internet Tools

• Hytelnet

• Archie

• Gopher

• WAIS

• World Wide Web (WWW)

Hytelnet

• A tool for working with Telnet.

• Using Hytelnet you may get an organized collection of sites and services available through Telnet.

• You browse the collection using a hypertext interface.

Archie

• Lets you search the archives of files accessible by anonymous FTP.

• Search is done using the complete or partial name of a file and the answer is the Internet address and location of files.

Gopher

• A menu-based document delivery system.

• Provides access to information such as files, documents, address books, and images.

• Also allows access to ftp, telnet, and searchable databases.

• Veronica is a tool to search Gopher menus for resources throughout the Internet.

WAIS

• Wide Area Information System

• A system for searching and retrieving items from databases.

• Search is done using one or more keywords. The result is a list of articles arranged in a list. These articles you can view on the screen, save to a file, or send to an Internet address via e-mail.

WWW

• World Wide Web• A single means of access to almost everything

available through the Internet: services, resources, tools, and information.

• Gives hypertext, and hypermedia access (i.e. links to other pages, documents, etc.)

• Programs that work with the WWW are the Internet Explorer, Netscape Navigator and before these Lynx, and the Mosaic.

How the Internet Works

• The Internet is a network connecting thousands of other computer networks.

• Each network has a unique address, and each computer connected to a network has its own address. Examples of addresses: 194.65.245.76 or sage.my.edu.

• Computer systems within one network can exchange information with computers on other networks.

How the Internet Works (Cont.)

• The rules that govern this form of communication are called protocols.

• Two protocols used are Internet Protocol (IP) and Transmission Control Protocol (TCP)

• Packets of characters (bytes), with the receiver’s address, carry information on the Internet. These packets are passed from one network to another until they reach their destination. --> The Internet is a packet-switched network.

How the Internet Works (Cont.)

• The networks on the Internet use a hardware device called router to communicate with other networks.

• The router accepts packets addressed to it and passes on packets addressed to other networks.

How the Internet Developed

• In the late 1960s the United States Department of Defense funded the ARPANET project.

• ARPA (Advanced Research Projects Agency).• ARPANET linked researchers at universities,

research laboratories, and some military labs.• NSFNET was developed to connect supercomputer

centers in the United States.• The network kept expanding with more and more

computer connections in U.S. and overseas.

How the Internet Developed (Cont.)

• Other commercial networks and free-nets were developed.

• The Internet has grown very rapidly into something that involves millions of people worldwide.

Internet Domain Names and Addresses

• An address is assigned to each network, and each computer within a network gets an address based on the network’s address. Example: 195.65.245.76

• From left to right, a first group of numbers identifies a network (e.g. 195.65.245), and a second group a specific host or computer system (e.g. 76). This numeric address is called an IP (Internet Protocol) address.

Internet Domain Names and Addresses (Cont.)

• Domain names may be assigned to the numbers in the IP address. Example: sage. myu.edu where sage is the computer name, and myu.edu the network name. The last 3 characters (edu, com, gov, mil, net, org) usually denote the type of organization.

• Documents are retrieved from the WWW using a URL (Uniform Resource Locator) address.

Internet Domain Names and Addresses (Cont.)

• Example of a URL address:

http: www.ee.ic.ac.uk/misc/country-codes.html• General form of a URL address:

service://domain-name-of-site-supplying-service/full-path-name-of-item

(http stands for hypertext transport protocol)