CSIT 58: The Internet

On the Internet you can: Send and receive email Do research Play games or gamble Get copies of programs and music Get breaking news Ecommerce: Buy and sell, bank Communicate with chat and phone calls And much more…

What is the Internet?

A world-wide computer network made up of tens of thousands of smaller networks. It’s the biggest network of all!

Then what is a network?

A network is a collection of computers and other devices that communicate to share data, hardware and software. A server coordinates the sharing.

Computer Networks

Network Servers

A server is a computer running special network operating system software that allows it to process requests from other computers that it is connected to.

Physical Connections

Computers communicate with the server through cable, phone lines, wireless broadcast or satellite. There are different types of servers on the Internet for:

web pages e-mail

ftp (file transfer) media

Routers

A router controls connection points between networks.

It sends data to the proper destination and provides security features.

If you have multiple PCs at home with a single cable or DSL Internet connection, the computers can share the connection with a router.

TCP/IP Networking

A protocol is a set of rules that determine how communication takes place. TCP/IP is the communications protocol used on the Internet to transfer information from computer to computer. It allows many different types of computers to exchange data in packets

The Internet Backbone

Network service providers (NSPs) maintain a series of communications links called the Internet backbone.

The NSPs are major communications companies like AT&T, Verizon and Sprint.

No one “owns” the Internet. The computers on it are owned and operated by individuals and organizations.

The Internet is decentralized – there is no main computer that all packets must go through.

ISP Internet Service Provider

Businesses, organizations and home users contract with an ISP for access to the Internet.

An ISP maintains communications equipment to connect to the backbone.

Sign up with an ISP

Your account with a service provider usually gives you: Access to the Internet An email address Storage for a web page Security features

How to Connect to the Internet

Since the Internet is a world-wide network of smaller networks, your computer must become part of that network for you to have access.

There are several different ways…

Be On a LAN Connected to the Internet The LAHC computer labs are connected in a

local area network (LAN) that gives access to campus servers for printing and programs.

The LAN is also connected to the Internet through a router. Your work may be set up this way also.

LAHC pays to connect to high-speed Internet through a special phone line.

Methods for Connecting

You’re not connected to a LAN at home, so you need to make a physical connection to the Internet network through:

Phone linesCable TVWirelessSatellite (used in remote areas, expensive)

The Phone LinesPhone companies provide connection options for homes and businesses. From slowest and cheapest on up they are:

•Dial-up

•DSL

• Fiber-optic (FIOS by Verizon)

Dial-up Using Standard Phone Lines

Phone lines are analog (for sound waves). Computers are digital. A modem must be installed in the PC to convert the signals back and forth. Most computers come with one.

A cable runs from the back of the computer to the wall jack. You can’t talk on the phone while connected to the Internet.

Modem speeds are 56Kbps (thousands of bits per second)

DSL

DSL is a high speed connection that runs over existing phone lines. You must be within 3 miles of a telephone switch for it to function well. Contact your local phone company to find out if it works in your area.DSL costs more than dial-up, but is much faster, up to 1.5 Mbps (M=millions).

Cable TV Internet Access

Connect through cable TV system.

There are 500 households per neighborhood connection point for Cox. 2 or 3 big downloaders can slow response time for everyone.

Speed varies. Can be over 1.5Mbps.

Cable TV and DSL

Cable and DSL Internet require a network board installed in the PC.A cable runs from this to an external modem box or router. Connection is always-on, when your computer is on you are on the Internet.Called broadband because of high data capacity

Wireless (Wi-Fi)

A WISP maintains a public wireless network. A hotspot is a location where a PC equipped with a wireless card can connect to the network. Advantage is portability, no cables are needed.Available in airports, hotels, restaurants, college campuses, the LAHC cafeteria, Library and Seahawk Center.Disadvantages: slow, not secure, susceptible to interference

What is the Web?

The World Wide Web is a collection of data that can be linked and accessed using HTTP

HTTP (“hypertext transfer protocol”) is the communication standard of the Web

A Web page is specially coded document that can contain text, graphics, videos, and sounds

A Web server is computer that runs special Web server software and can send Web pages via Internet

A Web site consists of one or more Web pages located on Web server

Browser Software

Browser software runs on your PC and requests and displays web pagesExamples are:

Internet Explorer (IE) Mozilla Firefox Netscape Navigator AOL

URL

A URL is the address of a web page.

You enter a URL in the browser or click a link to a page and the browser software requests the page from the web server.

HTML

Web pages are stored in HTML format (.htm ending). HTML is a set of instructions that the browser interprets to display the page.

For example, <U>Internet Backbone</U> would cause the words Internet Backbone to display underlined as shown.

How do I use a URL to go to a Web site? To enter a URL:

Click Address box on browser window Type URL Press Enter key Browser formats and displays page on screen

Be very precise when entering URL Don’t use any spaces Exactly duplicate uppercase and lowercase letters

Complete URL usually starts with http:// Don’t have to type this, browser fills in

How do I use a URL to go to a Web site? Cont’d.

The part of a URL after the dot indicates top-level domain of URL Most commercial and e-commerce use .com

domain .biz and .info are new Educational institutions use .edu U.S. government agencies use .gov U.S. military use .mil International Web sites use .int or country

abbreviations such as .ca for Canada, or .fr for France

How do I use links on a Web page? A hypertext link (“link”) is a connection between

two Web pages Contains URL of Web page, so it can be used to

“jump” from one Web page to another Links usually displayed on Web page as underlined

text or as graphic When positioned over a link, arrow-shaped pointer

turns into When you click link, Web page displayed

The Stop and Home buttons

If you don’t want to wait for the Web page to load, click Stop button (a red X) Then click different link or enter new URL

Click the Home button (a house) to display the home page set in Tools, Options

The Refresh button

Refresh button (one or two curved arrows) reloads current page from the server

If page loads slowly, click Stop button then click link again or click Refresh Sometimes page loads faster If still slow, try different link or different

URL

The Back and Forward buttons

Back button (backward pointing arrow) displays last page viewed Click several times to view series of pages

Forward button (forward pointing arrow) does not take you to new page but counters Back button

When browser first started, Back and Forward buttons disabled or “grayed” out Back button enabled when you go to new page Forward button enabled after Back button used

The History list

The History list displays titles and/or URLs of Web pages you visited in past To access IE’s History list, click History button on

right side of Address box or the down arrow next to the Forward button (IE 7).

In Firefox, click the History button in the menu bar.

The Site list displays URLs of previously visited Web sites To access the site list, click down-arrow button on

right side of Address box

Use Favorites (Bookmarks)

To save the link to a page you are viewing: For IE version 7 click the button with the plus sign

and star. For earlier versions click the Favorites button and then Add.

For Firefox, click Bookmark this page in the Bookmarks menu.

To visit a saved Web site: In IE click the Favorites button (the star) to open

list and clicking page you want In Firefox click Bookmarks in the menu bar.

Use Favorites Cont’d.

As you add favorites, you can create folders to group them into.

To delete a site or folder from list, right-click site name, then click Delete on shortcut menu

How do I print a Web page?

Click Print button in toolbar or select File, Print from the menu bar

Some Web pages include a link to a “print friendly” version of page Designed to use color in way that single page won’t

use all your printer ink Look for “printer friendly” link before you start

printout Use File, Print Preview (in IE7 click the arrow

next to the printer and choose Preview) to make sure you’re not printing a huge number of pages.

What should I do when I get an error message?

If a Web page can’t be loaded, the browser eventually displays an error message

If a URL is not mistyped, the message probably means the page has moved, was renamed, or deleted

Occasionally a message appears if the site is too busy to respond – try later

Temporary FilesAs you use the Internet, information may

be stored on your hard drive in temporary files. Delete these to free up space. In IE, go to Tools, Internet Options,

Browsing History, Delete. From there you can remove temporary files, history, saved passwords and cookies.

Firefox displays a box asking you to delete temporary files as they are used. For other data, go to Tools, Clear Private Data

Plug-Ins

Non-HTML Web elements – video clips, animation – might require special viewing software Referred to as plug-ins or helper

applications Typically downloaded from Web Popular plug-ins include RealMedia Player,

and QuickTime viewer Articles I post for you to read require

Adobe Acrobat reader for .pdf format

What is a search engine?

A Search engine is a site that provides tools to help find information Google, Ask, Live Search and Yahoo!

Provides list of Web pages based on keywords you enter in a search query.

Read my notes on searching and then practice using search engines in the assignment.

End of Lecture