Transcript Slide 1

WHAT IS THE INTERNET?
A network is made up of two or more connected computers
that share information.
An internet is a connected group of networks.
The Internet is an international connection of computer
networks that communicate with each other using the
same protocol.
Computers can be connected with wires, cables, or via
satellite.
Hundreds of countries, thousands of organizations, and
millions of computers are connected to the Internet.
More than 25 million people use the Internet each day!
• The Internet is a network of computers spanning
the globe.
• This communication structure is a system
connecting more than fifty million people in
countries around the world.
• A global Web of computers, the Internet allows
individuals to communicate with each other.
• Often called the World Wide Web, the Internet
provides a quick and easy exchange of
information and is recognized as the central tool
in this Information Age.
Network
• Computer Networks (or Networks) are two
or more computers connected together to
share resources.
• Two or more networks connected together
form an internet.
Protocol
• Protocol is a uniform computer standard
that allows computers to communicate
with one another.
• TCP/IP (Transmission Control
Protocol/Internet Protocol) is the protocol
for computers that are on the Internet.
• Every computer on the Internet is part of a
network.
• It is these connections of computers that
make-up the International Network -- or
the Internet.
HISTORY OF THE INTERNET
• The Internet was originally created in the
1960's as a government-sponsored
computer network for the United States
defense industry.
• Over the years, as the Internet became a
more powerful and sophisticated way to
share information, universities and
corporations began using it.
• The Internet is made up of five strands or
resources:
• Gopher
• FTP
• Telnet
• USENET news grous & Electronic Mail
• World Wide Web
• Most people use the terms Web, World Wide
Web, or WWW to refer to the entire Internet, but
the Web is only one part of the Internet.
• The Web can access ALL other parts of the
Internet: Gopher, FTP, USENET, etc.
• The Web works by moving information from
server computers to client computers using Web
browser software (Netscape®, Internet
Explorer®, and others).
• Some of these Internet strands, like
Gopher, FTP, and Telnet were popular in
the early years, but were not always easy
to use. They were also limited in the kinds
of information that they could move from
computer to computer. Gopher, FTP, and
Telnet were limited to text files or word
files.
• Files containing graphics, images,
pictures, sound, or video could not be
shared until the Web was invented.
• These days, electronic mail and the Web
are the most popular Internet strands.
WHAT IS THE WORLD WIDE WEB?
• The World Wide Web is the graphical interface strand of
the Internet.
• It allows text files and multi-media files -- graphics,
pictures, moving images, video and movies, and
audio/sound -- to be sent and received over the Internet.
• The Web also recognizes and leads users to the other
four Internet strands (Gopher, FTP, Usenet, and Telnet),
making the Internet more seamless and easy to use.
• The Web itself does not exist at any one
place.
• It is truly a web of interconnected
documents, files, and computers that
together create this thing called the Web.
• Like the Internet itself, the Web is
constantly changing and evolving as new
information is added and expanded.
HISTORY OF THE WEB
• The Web was invented in 1989 by Tim Berners-Lee and other
physicists at the European Particle Physics Laboratory (CERN) in
Geneva, Switzerland. They invented the Web because they wanted
to use the Internet to share documents that contained both text AND
pictures and images (multi-media).
• The first Web browser -- the computer software that lets us use the
Web -- was released in 1993 by the National Center for
Supercomputing Applications (NCSA). It was called Mosaic®. This
first Web Browser allowed computer users to use a mouse to move
through the Web, and also allowed for graphics and other media to
be used in Web documents.
• There are dozens of Web browsers on the market today. Most of us
use Netscape® or Internet Explorer®.
Web Browsers
• Web Browsers are software that allow your
computer to display Internet resources.
• Web browsers are also referred to as ?client
programs? because they allow your computer
(the client) to read documents or files that come
from a server computer.
• The first Web browser, Mosaic?, was invented in
1993.
• Netscape? and Internet Explorer? are two
popular Web browsers in use today.
BASIC WEB FUNCTIONS
• Any person with Internet access and a Web browser can
create a Web site, and any person with Internet access
and a Web browser can use that Web site. This allows
for individuals, universities, corporations, governments ?
anyone and everyone ? to share information on the Web.
• The computer that sends the documents or Web pages
is called the server. The computer that receives or reads
the documents is called the client. Any computer can be
a server, and any computer can be a client.
BASIC WEB FUNCTIONS
• Web sites and pages move from computer to computer
something like this:
• When you browse the Web, your computer (client)
sends out an HTTP request to a server (the computer
which houses the requested information).
• The server then sends back an HTML -- hypertext
markup language Web page. Web documents or
"pages" are usually written in HTML or similar Web
"languages".
• HTTP (hypertext transfer protocol) is the computer
protocol that can read HTML documents or pages.
URL
• A URL -- Uniform Resource Locator
(usually pronounced like the name "Earl")
is an address on the Web.
• Just like every house has a street address,
every Web site has a URL.
URL: AN ADDRESS ON THE WEB
URL FORMATS
• URLs follow a particular format or pattern, providing
information about the Web site that you are using:
URL FORMATS
• This is the basic format that a URL follows:
protocol://server & domain/directory/file & extension
This is the URL for the Yahoo® search engine:
http://www.yahoo.com
This is the URL for the page that you're reading right
now:
http://med-libwww.bu.edu/library/tutorial/url.html
DOMAIN NAMES
• DOMAIN NAMES AND TOP LEVEL DOMAINS
(TLD)
• Now we know what a URL is, and have seen the
parts of a URL, or Web address. Let's talk about
Domains.
• A domain is the unique name that identifies a
Web site. The last (right-hand) part of a domain
name is called the Top Level Domain (TLD).
• For example, in the domain name
www.yahoo.com, the .com is the Top
Level Domain (TLD).
• Top Level Domain names give us a lot of
information about a Web site: who
created, sponsors, or produces the
information on the site; its intended
audience or intended users; and so on.
COUNTRY CODE
• COUNTRY CODE TOP LEVEL DOMAINS
(ccTLD)
• Two letter domains are called Country Code
Top Level Domains (ccTLD), and correspond
to a country, territory, or other geographic
location outside of the United States.
• For example, if we were looking for news in
England, we might go to the BBC site:
www.bbc.co.uk
• Country Code Top Level Domain (ccTLD)
names are two-letter country codes that
represent the country or geographic region
in which a Web site originates.
• The United States also has a ccTLD (.us),
but because we are in the U.S., a .us code
isn't generally displayed.
VOCABULARY REVIEW
• Backbone
• A high-speed line or group of connections
that form a path in a computer network.
The term is generally used in reference to
smaller networks.
Client
• A software program that is used to transfer
information or documents from a server.
Clients can be located nearby or
thousands of miles away from the server.
A Web Browser is a type of client that
allows your computer to read information
on the Web.
Computer Network
• Computer Network (or Network)
Two or more computers connected
together to share resources. Two or more
networks connected together form an
internet.
Cookie
• Information that a server sends to a Web Browser that
the browser stores and sends back to the server when
additional information is exchanged. Cookies contain
information like user preferences, shopping cart
contents, registration information, etc. Web browsers can
be set-up to accept or not accept Cookies. Cookies can
be saved for short or long periods of time. Organizations
use Cookies to store information about users that can be
used to personalize services or resources, or enhance
communication between an organization and a particular
user.
• Cyberspace
A term that many people use to represent
the Web, Internet, or the variety of
information that is available via computer
networks.
• Electronic Mail (e-mail or email)
Messages that are sent from one person
to another, or to a large number of people,
via a computer. People exchange their email addresses with one another so that
they know where to send the messages.
• Domain or Domain Name
The unique name that identifies an Internet site.
Domain Names have two or more parts,
separated by dots. On the left of the dot is the
more specific part of the name; on the right of
the dot is the more general part of the name:
med-libwww.bu.edu
yahoo.com
mtv.com
• FTP (File Transfer Protocol)
An Internet resource that was very popular
before the Web was invented. FTP is a
way of moving files from Internet site to
Internet site, by allowing your computer to
login to another computer to retrieve
information. Like other Internet resources,
FTP can only transfer text files, and has
been largely replaced in popularity by the
Web.
• Gopher
Gopher was invented around 1993 at the
University of Minnesota, just before the Web
was invented. Gopher was a very popular
method of making text-based information
available on the Internet using menus to make
information easier to organize and find. As use
of the Web grew, Gopher became less popular
because it only allowed for the sharing of textbased files, and not multi-media files (graphics,
sound, video, etc.) But, thousands of Gopher
servers are still on the Internet to this day.
• HTML (HyperText Markup Language)
The language that is used to write
hypertext on the Web. HTML files are
viewed using a Web browser.
HTTP
• (HyperText Transfer Protocol)
The protocol (a standard) for sharing
hypertext files on the Internet. HTTP
requires a client on one end, and a server
on the other. HTTP is the most popular
protocol for sharing information on the
Web.
•
• ISP (Internet Service Provider)
A company or organization that provides
Internet access, usually for a monthly fee
(America Online®, CompuServe®, and
many others).
• IP (Internet Protocol address)
In order to be on the Internet, every computer must have
a unique IP address. An IP address is a combination of
numbers that are made up of four parts, separated by
commas:
155.32.412.2
An IP number is like a URL or a domain name. But,
instead of using words, it uses numbers. While every
computer on the Internet must have an IP address, not
every computer has to have its own URL or domain
name, because URLs and domain names are for
computers that are sharing information, NOT receiving it.
TCP/IP
• TCP/IP (Transmission Control
Protocol/Internet Protocol)
The protocol (or standard) that defines the
Internet. To be "on the Internet," a
computer must have the TCP/IP software
so that it can communicate with other
computers.
• USENET news groups
Discussion groups that allow hundreds or
thousands of people all over the world to
share information and comments about a
variety of topics. The 10,000+ topics of
interest are called newsgroups. USENET
computers may or may not be on the
Internet.
Web Browser
Software (like Netscape® or Internet Explorer®)
that allows your computer to display Internet
resources.
Web browsers are also referred to as "client
programs" because they allow your computer
(the client) to read documents or files that come
from a server computer.
The first Web browser, Mosaic®, was invented
in 1993. Netscape® and Internet Explorer® are
two popular Web browsers in use today.
• WEB BROWSERS: IMPORTANT
INFORMATION BEFORE WE BEGIN