E-Mail, Networks, and the Internet

Electronic Mail (E-Mail)

• Means of communication between peoples using computer networks.
• Requires an account on a computer with access to a large network
• Free for Union Students with accounts on IDOL

Computer Networks

Several computers connected together in order to:

1. communicate
2. share resources

Local Area Network (LAN)

• Faster due to shorter distance (usually one room)
• Primary use is resource sharing (Printers, File Servers...)
• Uses dedicated cables to connect machines together
• Example is our classroom in Olin
• A server is the main computer in a LAN whose role is to
  1. coordinate messages between the other computers in the LAN
  2. hold original software that other machines in LAN can use

Wide Area Networks (WAN) a.k.a. Long Haul Networks (LHN)

• Much larger distances (therefore, slower)
• Can use satellite links or phone lines to connect nations around the world!
• Primary use is communications.

Internet

• The term "internet" in general refers to a combinations of LANs and WANs that extends a great distance and includes many types of computers.
• The "Internet" is a specific global network that was originally a Defense Project for U.S. (DARPA). It extends all over the world and is currently self-run and self-policed.

Addresses

• All computers on the Internet have an address
• All users (accounts) on any one computer have specific addresses
• Analogous to a Postal Address

• Format:

  username@computer.organization.type

  Examples:

  smithj@idol.union.edu

  fernandc@snarf.union.edu

UNIX: Another operating system

• A different OS used by IDOL
• It is a Command Line Interpreter (CLI): commands typed in one line at a time at a prompt
• UNIX is case sensitive: "Logout" is different from "logout"

• Example UNIX commands:

  cd = change directories

  ls = list files in directory

  cp = copy files

  elm = electronic mail program

  logout = end session and disconnect

  telnet = connect to remote computer

  ftp = connect to a remote computer to transfer files

  man = obtain help for UNIX command. Type man and then the name of the command

Using a Web Browser

What is it not?

• A web browser is not the Internet.
• A web browser is not the World Wide Web.
• A web browser is not an operating system.

Ok, then what is it?

• A web browser is a program whose task it is to interpret and display World Wide Web (WWW) documents. These are documents written in a markup language; most commonly, HTML. Common examples of browsers are MS Internet Explorer, Netscape, Safari, Opera, and Firefox.
• A browser displays WWW files by going to where a file is located. This is identified by a URL (Uniform Resource Locator.)

Searching and Surfing

• anything in blue is hypertext: click it for more info

• use a search engine to perform a search of the WWW

  for example, Google is a search engine.

• save a page you've found with a bookmark so you don't have to remember the URL

Making your own web pages (learning HTML)

• Hypertext Markup Language (HTML) uses tags to denote instructions
• tags used to denote formatting, pictures, text, sound, hypertext, etc.
• examples of tags (italicized words get replaced appropriately):
  • <img src="filename"> for pictures
  • <a href = "URL">hypertext</a> for a link
  • <P> for a new paragraph
• not WYSIWYG so as to accommodate all browsers on all computers
• For more information, check out our own CSc 050 web tutorials