Transcript Introduction to the Internet

CSCI 1101 Intro to
Computers
7. Introduction to the
Internet
ACS 160 - Chapter 8 - The Internet
What is cyberspace?
The term Cyberspace, a computer-generated
world that exists in a hazy realm between reality
and imagination, was coined in 1984 by science
fiction writer William Gibson.
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ACS 160 - Chapter 8 - The Internet
What is the "Internet"
The Internet, which has been evolving for over
the past 30 years, is a collection of local,
regional, national, and international computer
networks linked together to exchange data and
distribute processing tasks.
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Brief history of the Internet
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The United States created ARPA (Advanced
Research Projects Agency).
 to
help scientists communicate and share
valuable computer resources
 in response to the Soviet Union’s launch of
Sputnik in 1957, the first artificial satellite
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The ARPANET, created in 1969, connected
computers at four universities.
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Continuing definitions of Internet
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Connecting two or more networks creates
an “internetwork” or “internet.”
The Internet is huge and continues to grow.
 size
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can only be estimated
Internet host - a computer on the Internet
that provides services
 data
routing
 e-mail
 Web pages
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Size of the Internet's data
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Internet traffic - the number of bytes
transmitted from one Internet host computer to
another
 exceed
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100 terabytes per week in 1997
Michael Dertouzos, director of the MIT
Laboratory of Computer Science, estimates
that the world has 1 exabyte to store data.
Exabyte - 1 quintillion bytes.
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How the Internet works
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A network service provider (NSP)
maintains a series of communications links
for Internet data.
 links
connect at network access points (NAPs)
 major Internet links are called the Internet
backbone
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TCP/IP (Transport Control Protocol/Internet
Protocol) - computer rules used by every
computer that connects to the Internet
ACS 160 - Chapter 8 - The Internet
How to gain access to the Internet
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You connect to the Internet by connecting to an
Internet Service Provider (ISP) which connects to
the Internet backbone.
ISP - company that maintains an Internet host
computer
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provides Internet access to businesses and individuals
charges monthly fee
offered over telephone lines, cable TV, or satellite dish
Dial-up connection - a connection that uses a
phone line to establish a temporary Internet
connection
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Internet addresses
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Every computer that connects to the Internet has a
unique number called an IP address.
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A router examines the IP address and then forwards the
data to its destination.
Many host computers have an easy-to-remember name
which is officially called a fully qualified domain name.
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most people call it a domain name
Domain name
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set of four numbers between 0 and 255
separated by periods
typed in lowercase
ends with three letter extension which is its top-level domain
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What is a web-site really?
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A computer with a domain name is referred to
as a site.
Web site - location in a computer somewhere
on the Internet.
Original Internet Top-level domains
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How are Web-sites and Web-pages
different?
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Web sites are composed of a series of Web pages.
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URL (Uniform Resource Locator) - an Internet address
of a document on a computer
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each page stored as a file
referred to by a unique URL
begin with http://
HTTP stands for Hypertext Transfer Protocol - the
protocol that allows Web browsers to communicate
with Web servers.
ACS 160 - Chapter 8 - The Internet
How do pages get "on" the
Internet?
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Web server - computer with special software
for transmitting Web pages over the Internet
 Most
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domain names prefixed with www
Home page - identifies the site and typically
contains links to other pages at the site
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Is the Web and the Internet one and
the same?
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The Web is only one of the Internet’s many
services.
The Internet also provides
 e-mail
 file
transfers
 discussion groups
 real-time chat
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Other Internet services
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The Internet also includes FTP servers which
maintain files that you can transfer to your own
computer.
Usenet servers and IRC servers handle
exchange of comments among members in
chat groups.
ACS 160 - Chapter 8 - The Internet
What is the role of Web browsers?
Web browsers provide Internet users with allpurpose client software for accessing many types
of servers.
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Origin of the Web
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The World Wide Web, or “the Web” was
created in 1990 at the European Laboratory for
Particle Physics.
The Web
 Internet
service that stores and provides information
 easy to use source of graphical information
 consists of documents (Web pages) that contain
information on a particular topic
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How web-pages provide linkage
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A Web page may contain links that point to
other Web pages.
 makes
it easy to follow a thread of related
information
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You request a Web page from a Web browser
by typing in a URL or clicking a Web page link.
The page that displays when your browser first
starts is called the home page
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What is a Web Portal?
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A Web portal is a Web site that provides a
group of popular Web services.
 search
engines
 e-mail accounts
 chat rooms
 links to shopping, weather, news, and sports
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Some current web portals
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Popular Web portals include America Online,
GO Network, Lycos, and Yahoo
Some portals are maintained by commercial
information services.
 also
serve as ISPs
 charge monthly membership fee
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Content of a Web Page
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Web pages now include multimedia elements
such as sound, animation, and video.
 stored
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in a file
Streaming media - computer plays a media
file while receiving it
In-place multimedia technology - plays a
media element as a seamless part of a Web
page
ACS 160 - Chapter 8 - The Internet
Simple animated Gifs
This animated gif plays in
place as part of the Web
page.
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More robust multi-media
techniques
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Multimedia overlay technology adds a
separate window to your screen for
multimedia elements.
Multimedia overlay
technology
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Browser add-ons
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A software module that provides your
computer with the capability to view or
play a specific type of file is called a
player, plug-in, or viewer.
The Web browser maintains list of media
players installed on your computer.
 most
browsers provide a link to a site where
you can download a necessary player
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Download vs. Upload
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Downloading is the process of transferring a
file from a remote computer to your computer.
1. Right-click the
picture you
want to copy.
2. Choose
Save Picture as
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Download vs. Upload (cont.)
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Uploading - the process of sending a copy of
a file from your computer to a remote computer
You can upload files using FTP client software,
such as WinFTP.
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How to download software
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The Internet is a good source of free software.
Most downloadable software is stored as a
self-extracting file, a single file that holds all
of the modules for the software.
 download
software
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sites include instructions for downloading
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Example of software available on
the Web
You can take
advantage of
thousands of
shareware,
freeware, and
trial versions of
software.
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Other Internet activities
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In addition to e-mail, people can interact on the Internet
by joining a discussion group.
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takes place asynchronously, meaning discussion participants
are not online at the same time
A chat group is a discussion group which takes place
synchronously (participants are online at the same
time).
Multi-player gaming - gives you an opportunity to play
with or against, other players all over the Internet
ACS 160 - Chapter 8 - The Internet
HTML Authoring tools
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In addition to using HTML, Web authoring
tools make it much easier to create Web
pages.
 use
word processor-style interfaces
 wizards
 predesigned templates
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Popular Web authoring software includes
Microsoft FrontPage and Claris Home Page.
 contain
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tools for managing Web sites
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Web page guidelines
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Plan your Web page so that it fulfills its purpose.
Design a template to unify your pages.
Follow basic rules for good Web page design:
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narrow line widths
proofread
use contrasting colors; do not use drab colors
do not use overly large graphic files
use graphics with .jpg or .gif filename extensions
use thumbnails to link to larger version of large graphics
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More web page guidelines
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Identify your pages.
Include dates.
Include navigational elements.
Respect the copyright and intellectual
property rights of other Web sites.
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How do businesses use the web?
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E-commerce refers to buying products and services
by means of the Internet.
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online shopping
online auction sites
Like big businesses, individuals can also set up their
own e-commerce site.
Many Web hosting services and portal sites offer an
e-commerce enabled Web site, which simplifies
the process of constructing an online storefront.
ACS 160 - Chapter 8 - The Internet
The role of an ISP
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An Internet Service Provider (ISP) connects
you to the Internet by providing you with a user
account on a host computer that has access to
the Internet.
Internet connections are also available through
commercial information services, such as AT&T
WorldNet and America Online, and some cable
TV companies.
 charge
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$10 - $40 per month
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Physical connections
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Most people use a telephone line to access
the Internet.
 can
also use cable, cellular phone, or personal
satellite dish
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You need a computer, modem, and telephone
line.
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Connection speeds
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Connection speed is the maximum
speed that your modem can communicate
with the ISP’s modem.
Transfer rate is the speed at which you
can send or receive data.