Transcript Document

Compiled by :
S. Agarwal, Lecturer & Systems Incharge
St. Xavier’s Computer Centre,
St. Xavier’s College
Kolkata
March-2003
Compiled by : S. Agarwal, Lecturer & Systems Incharge, St. Xavier's Computer Centre, Kolkata : [email protected]
Clients and Servers:
In general, all of the machines on the Internet can be
categorized as two types: servers and clients.
Those machines that provide services (like Web servers
or FTP servers) to other machines are servers. And the
machines that are used to connect to those services are
clients.
Compiled by : S. Agarwal, Lecturer & Systems Incharge, St. Xavier's Computer Centre, Kolkata : [email protected]
When you connect to Yahoo!
at www.yahoo.com to read a page,
Yahoo! is providing a machine for use
on the Internet, to service your request.
Yahoo! is providing a server.
Your machine, on the other hand, is
probably providing no services to
anyone else on the Internet. Therefore,
it is a user machine, also known as a client.
Compiled by : S. Agarwal, Lecturer & Systems Incharge, St. Xavier's Computer Centre, Kolkata : [email protected]
A server machine may provide
one or more services on the
Internet.
For example, a server machine
might have software running on
it that allows it to act as a Web
server, an e-mail server and an
FTP server.
Compiled by : S. Agarwal, Lecturer & Systems Incharge, St. Xavier's Computer Centre, Kolkata : [email protected]
WEB SERVER
Caters to internet clients to provide
web-pages. It stores the text, graphics,
and other information in the form of
web pages. The web pages are mainly
developed using HTML.
HTML : Stands for Hyper Text Markup Language.
A special language used to prepare web pages and
display information using Browsers.
Compiled by : S. Agarwal, Lecturer & Systems Incharge, St. Xavier's Computer Centre, Kolkata : [email protected]
E-MAIL SERVER
Caters to e-mail clients acting the same way
as the post box in a post office. Stores
incoming mails and transfers outgoing
mails to the e-mail server of the recipient.
In the e-mail addresses the part after @
denotes the mail server address.
[email protected]
[email protected]
Compiled by : S. Agarwal, Lecturer & Systems Incharge, St. Xavier's Computer Centre, Kolkata : [email protected]
FTP SERVER
Abbreviation of File Transfer Protocol, the protocol
used on the Internet for sending files. The server
stores the files that can be downloaded by
the clients.
Files stored in these servers can be
downloaded / uploaded through FTP
programs which allow us to connect to the
ftp port.
Compiled by : S. Agarwal, Lecturer & Systems Incharge, St. Xavier's Computer Centre, Kolkata : [email protected]
IP Addresses:
To keep all of these machines straight, each
machine on the Internet is assigned a unique
address called an IP address. IP stands for
Internet protocol, and these addresses are 32-bit
numbers, normally expressed as four "octets" in a
"dotted decimal number." A typical IP address looks
like this:
216.27.61.137
The four numbers in an IP address are called
octets because they can have values between 0
and 255, which is 28 possibilities per octet.
Compiled by : S. Agarwal, Lecturer & Systems Incharge, St. Xavier's Computer Centre, Kolkata : [email protected]
Every machine on the Internet has a
unique IP address. A server has a static
IP address that does not change very
often. A home machine that is dialing up
through a modem often has an IP
address that is assigned by the ISP when
the machine dials in. That IP address is
unique for that session -- it may be
different the next time the machine dials
in. This way, an ISP only needs one IP
address for each modem it supports,
rather than for each customer.
Compiled by : S. Agarwal, Lecturer & Systems Incharge, St. Xavier's Computer Centre, Kolkata : [email protected]
If you are working on a Windows machine, you can
view a lot of the Internet information for your machine,
including your current IP address and hostname, with
the command WINIPCFG.EXE (IPCONFIG.EXE for
Windows 2000/XP).
Compiled by : S. Agarwal, Lecturer & Systems Incharge, St. Xavier's Computer Centre, Kolkata : [email protected]
As far as the Internet's machines are
concerned, an IP address is all you need
to talk to a server. For example, in your
browser, you can type the URL (Uniform
Resource Locator)
http://209.116.69.66
and arrive at the machine that contains
the Web server for HowStuffWorks.
Compiled by : S. Agarwal, Lecturer & Systems Incharge, St. Xavier's Computer Centre, Kolkata : [email protected]
Domain Names:
If we had to remember the IP addresses of all of
the Web sites we visit every day, we would all go
nuts. Human beings just are not that good at
remembering strings of numbers. We are good
at remembering words, however, and that is
where domain names come in. You probably
have hundreds of domain names stored in your
head. For example:
•www.howstuffworks.com - a typical name
•www.yahoo.com - the world's best-known name
•www.mit.edu - a popular EDU name
•encarta.msn.com - a Web server that does not start with www
•www.bbc.co.uk - a name using four parts rather than three
•ftp.microsoft.com - an ftp server rather than a Web server
Compiled by : S. Agarwal, Lecturer & Systems Incharge, St. Xavier's Computer Centre, Kolkata : [email protected]
The COM, EDU and UK portions of
these domain names are called the toplevel domain or first-level domain. There
are several hundred top-level domain
names, including COM, EDU, GOV,
MIL, NET, ORG and INT, as well as
unique two-letter combinations for every
country.
Compiled by : S. Agarwal, Lecturer & Systems Incharge, St. Xavier's Computer Centre, Kolkata : [email protected]
Within every top-level domain there is a huge
list of second-level domains. For example, in
the COM first-level domain, you've got:
•howstuffworks
•yahoo
•msn
•microsoft
•plus millions of others...
Every name in the COM top-level domain
must be unique, but there can be duplication
across
domains.
For
example,
howstuffworks.com and howstuffworks.org are
completely different machines.
Compiled by : S. Agarwal, Lecturer & Systems Incharge, St. Xavier's Computer Centre, Kolkata : [email protected]
In the case of bbc.co.uk, it is a third-level
domain. Up to 127 levels are possible,
although more than four is rare.
The left-most word, such as www or encarta,
is the host name. It specifies the name of a
specific machine (with a specific IP address)
in a domain. A given domain can, potentially,
contain millions of host names as long as
they are all unique within that domain.
Compiled by : S. Agarwal, Lecturer & Systems Incharge, St. Xavier's Computer Centre, Kolkata : [email protected]
Name Servers:
Because most people have trouble remembering the
strings of numbers that make up IP addresses, and
because IP addresses sometimes need to change, all
servers on the Internet also have human-readable
names, called domain names. For example,
www.howstuffworks.com is a permanent, humanreadable name. It is easier for most of us to remember
www.howstuffworks.com than it is to remember
209.116.69.66.
The name www.howstuffworks.com actually has 3
parts:
1.The host name ("www")
2.The domain name ("howstuffworks")
3.The top-level domain name ("com")
Compiled by : S. Agarwal, Lecturer & Systems Incharge, St. Xavier's Computer Centre, Kolkata : [email protected]
Domain names are managed by a company called
VergiSign. VeriSign creates the top-level domain
names and guarantees that all names within a top-level
domain are unique. VeriSign also maintains contact
information for each site and runs the "whois" database.
The host name is created by the company hosting the
domain. "www" is a very common host name, but many
places now either omit it or replace it with a different
host name that indicates a specific area of the site.
For example, in encarta.msn.com, the domain name for
Microsoft's Encarta encyclopedia, "encarta" is
designated as the host name instead of "www."
Compiled by : S. Agarwal, Lecturer & Systems Incharge, St. Xavier's Computer Centre, Kolkata : [email protected]
A set of servers called domain name
servers (DNS) maps the human-readable
names to the IP addresses. These servers
store simple databases that map names to
IP addresses, and they are distributed all
over the Internet.
Most individual companies, ISPs and
universities maintain small name servers to
map host names to IP addresses. There are
also central name servers that use data
supplied by VeriSign to map domain names
to IP addresses.
Compiled by : S. Agarwal, Lecturer & Systems Incharge, St. Xavier's Computer Centre, Kolkata : [email protected]
If you type the URL
http://computer.howstuffworks.com/web-server.htm
into your browser, your browser extracts the name
"www.howstuffworks.com," passes it to a domain name
server, and the domain name server returns the correct
IP address for www.howstuffworks.com.
A number of name servers may be involved to get the
right IP address.
For example, in the case of www.howstuffworks.com,
the name server for the "com" top-level domain will
know the IP address for the name server that knows
host names, and a separate query to that name server,
operated by the HowStuffWorks ISP, may deliver the
actual IP address for the HowStuffWorks server
machine.
Compiled by : S. Agarwal, Lecturer & Systems Incharge, St. Xavier's Computer Centre, Kolkata : [email protected]
So here it is:
The Internet is made up of millions of
machines, each with a unique IP address.
Many of these machines are server
machines, meaning that they provide
services to other machines on the Internet.
You have heard of many of these servers:
e-mail servers, Web servers, FTP servers,
Gopher servers and Telnet servers, to
name a few. All of these are provided by
server machines.
Compiled by : S. Agarwal, Lecturer & Systems Incharge, St. Xavier's Computer Centre, Kolkata : [email protected]
Ports
Any server machine makes its services
available to the Internet using numbered
ports, one for each service that is available on
the server. For example, if a server machine is
running a Web server and an FTP server, the
Web server would typically be available on
port 80, and the FTP server would be
available on port 21. Clients connect to a
service at a specific IP address and on a
specific port.
Compiled by : S. Agarwal, Lecturer & Systems Incharge, St. Xavier's Computer Centre, Kolkata : [email protected]
Each of the most well-known services is available at a
well-known port number. Here are some common port
numbers:
•echo 7
•daytime 13
•qotd 17 (Quote of the Day)
•ftp 21
•telnet 23
•smtp 25 (Simple Mail Transfer, meaning e-mail)
•time 37
•nameserver 42
•nicname 43 (Who Is)
•gopher 70
•finger 79
•WWW 80
Compiled by : S. Agarwal, Lecturer & Systems Incharge, St. Xavier's Computer Centre, Kolkata : [email protected]
Protocols
Once a client has connected to a service on a
particular port, it accesses the service using a
specific protocol. The protocol is the predefined way that someone who wants to use a
service talks with that service. The "someone"
could be a person, but more often it is a
computer program like a Web browser.
Protocols are often text, and simply describe
how the client and server will have their
conversation.
Compiled by : S. Agarwal, Lecturer & Systems Incharge, St. Xavier's Computer Centre, Kolkata : [email protected]
To exchange information, computers must
understand what each other computer is
saying. They use a common language. We
use a common language in class, called
English. That is so we can understand what
is being said.
The common protocol (the language that
computers use to communicate with each
other) is TCP/IP, known as Transmission
Control Protocol, Internet Protocol.
Compiled by : S. Agarwal, Lecturer & Systems Incharge, St. Xavier's Computer Centre, Kolkata : [email protected]
ROUTER :
A router is a device that joins
telecommunications
links
and
groups of computers together. It
provides a way of finding a route (or
path) between the two computers
that want to exchange information.
Compiled by : S. Agarwal, Lecturer & Systems Incharge, St. Xavier's Computer Centre, Kolkata : [email protected]
WWW
The World Wide Web (WWW) is a collection of
host computers that deliver documents,
graphics and multi-media to users via the
Internet.
The common protocol used on the WWW is
HTTP. It stands for Hyper-text transport
protocol.
Each host computer on the World Wide Web
provides files in any format, such as a graphics
file, text document, powerpoint presentation or
audio file. Prior to the World Wide Web, the
display, searching, and viewing of files was
difficult and took a long time.
Compiled by : S. Agarwal, Lecturer & Systems Incharge, St. Xavier's Computer Centre, Kolkata : [email protected]
Advantages of the WWW:
•
The WWW lets users link documents together using
hyperlinks (a connection to another document on the
WWW).
 Easy linking of documents to other documents
 Documents are simple to create and make
available for other people to use
 Support for multiple multimedia components
in a single document (such as text, images,
sound and video)
 Access to anyone connected to the Internet
with a web browser
 Easy to publish and share information to other
people all around the world
Compiled by : S. Agarwal, Lecturer & Systems Incharge, St. Xavier's Computer Centre, Kolkata : [email protected]
The inventor of the WWW
was Tim Berners Lee.
The WWW is controlled by
the World Wide Web
Consortium in Geneva,
Switzerland.
Compiled by : S. Agarwal, Lecturer & Systems Incharge, St. Xavier's Computer Centre, Kolkata : [email protected]
Web Browser
A web browser is a software program that interprets
documents that you request from a web server on the
WWW. It displays them for you to view. The two
common types of web browsers are Netscape
Communicator and Internet Explorer.
Web Pages
Web pages are documents stored on web servers.
The pages are written in a special language called
HTML.
Hyper-Link
A hyperlink is a link to another document or resource.
It is often shown in blue underline. When a user clicks
on a hyperlink, the client browser gets the file
associated with that link.
Compiled by : S. Agarwal, Lecturer & Systems Incharge, St. Xavier's Computer Centre, Kolkata : [email protected]
URL?
A Uniform Resource Locator is where a file can
be found on the Internet. It is the pathname for
any resource on the Internet. It consists of three
parts
•a protocol part
•a host part
•a document name
Compiled by : S. Agarwal, Lecturer & Systems Incharge, St. Xavier's Computer Centre, Kolkata : [email protected]
Firewalls
A firewall is a device that protects a network
(group of computers) from outside interference.
Computers can be damaged by people using
the Internet. A firewall protects the computers
from damage.
A firewall is a router that restricts Internet
access by only allowing access to certain
computers (and specified services on those
host computers) within the organisation.
A firewall protects the company computers. It
can also stop company workers from accessing
the Internet!
Compiled by : S. Agarwal, Lecturer & Systems Incharge, St. Xavier's Computer Centre, Kolkata : [email protected]
Putting It All Together
When you type a URL into a browser, the following steps occur:
The browser breaks the URL into three parts:
1.The protocol ("http")
2.The server name ("www.howstuffworks.com")
3.The file name ("web-server.htm")
The browser communicates with a name server to translate the
server name, "www.howstuffworks.com," into an IP address, which
it uses to connect to that server machine.
The browser then forms a connection to the Web server at that IP
address on port 80.
Following the HTTP protocol, the browser sends a GET request to
the server, asking for the file
"http://computer.howstuffworks.com/web-server.htm."
The server sends the HTML text for the Web page to the browser.
The browser reads the HTML tags and formats the page onto your
screen.
Compiled by : S. Agarwal, Lecturer & Systems Incharge, St. Xavier's Computer Centre, Kolkata : [email protected]
Web browser :
Two of the most popular we browsers are
•INTERNET EXPLORER
•NETSCAPE NAVIGATOR
The functions and options of both the
browsers are similar. We shall discuss the
working of IE in the next few slides.
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Title Bar
Tool Bar
Address Bar
Menu Bar
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The Menu Bar
The menu bar lets you
•Change the way the pages are displayed
•Configure the web browser
•Open a document
•Print a document
•Save a document
•Find help
You can click on a menu and select what you want to
do. For example, to print the web page click File, then
Print.
Compiled by : S. Agarwal, Lecturer & Systems Incharge, St. Xavier's Computer Centre, Kolkata : [email protected]
Details of tool buttons (in sequence as shown in tool bar):
BACK
FORWARD
STOP
REFRESH
HOME
SEARCH
FAVOURITES
HISTORY
MAIL
PRINT
Go to the previous page
Go to the next web page
Stop downloading
Reload the page from server
Go to home page
Search the internet
List of favourite websites
List of sites visited recently
Open mail management application
Print the current web page
Compiled by : S. Agarwal, Lecturer & Systems Incharge, St. Xavier's Computer Centre, Kolkata : [email protected]
The Address Location Box
This box is used to type a URL (Uniform Resource
Locator, also called a Web Address). When you type an
address in this box, the web browser will try to find the
page. If it finds the page it will show it in the window.
Compiled by : S. Agarwal, Lecturer & Systems Incharge, St. Xavier's Computer Centre, Kolkata : [email protected]
Find text on page
You can find words on a web page. To find a word (or
phrase),
Click Edit, Find in Page on the menu bar
Enter the word or phrase you want to find in the Find
What box.
Click Find Next
If the word (or phrase) is found, it is highlighted in Blue
on the web page.
Only the web page in the display window is searched for
the word or phrase.
Compiled by : S. Agarwal, Lecturer & Systems Incharge, St. Xavier's Computer Centre, Kolkata : [email protected]
Bookmarks/Favorites
If you find a web site you like, you can write down the address. A
browser lets you keep a list of the sites you like. These sites are
called bookmarks or favourites.
When you add a bookmark / favourite , you tell the browser to
remember the site.
In IE toll bar click on
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Save a picture (image)
To save a picture on a web page,
1. move the mouse cursor over the picture
2. right click
3. select Save picture as
4. type a name and drive/folder to save the picture
Some pictures you can use on the Internet. Other pictures are
copyrighted. A copyrighted picture cannot be used without
permission.
Compiled by : S. Agarwal, Lecturer & Systems Incharge, St. Xavier's Computer Centre, Kolkata : [email protected]
How do I find Information on the Internet?
There is a lot of information available on the Internet.
Some of the information is useful. A lot of the
information is not useful. It is important to find
information quickly. A lot of time can be wasted. Useful
information can be found in internet with the help of
SEARCH ENGINES.
A search engine is a web server that searches for
information on the Internet.
Search engines create a list (called a database) of
resources they find on the WWW. People ask search
engines to add their web pages to the database.
Sometimes this is free. Sometimes you have to pay
money.
Compiled by : S. Agarwal, Lecturer & Systems Incharge, St. Xavier's Computer Centre, Kolkata : [email protected]
Compiled by : S. Agarwal, Lecturer & Systems Incharge, St. Xavier's Computer Centre, Kolkata : [email protected]
Here is a list of some search engines.
www.yahoo.com
www.google.com
www.dogpile.com
www.metacrawler.com
www.altavista.com
Compiled by : S. Agarwal, Lecturer & Systems Incharge, St. Xavier's Computer Centre, Kolkata : [email protected]
•
There are a number of ways a search engine knows about where information is
to be found.
1.
A search engine finds information using keywords or page titles. The
search engine looks at the web page. It gets the keywords from the
web page header. The keywords and the address of the page are
added to the database.
Keywords are written in the header using meta-tags. This is a special
way of writing information on a web page. It is used by search
engines. The web browser does not show meta-tags. It is quick. The
search engine only reads the header. It does not read all the web
page. This is called keyword indexing.
2.
A search engine reads all words on the web page. It makes a list of the
important words. The words and the address of page are added to the
database. It is slow. The search engine has to read all the words on
the page. This is called content indexing.
Compiled by : S. Agarwal, Lecturer & Systems Incharge, St. Xavier's Computer Centre, Kolkata : [email protected]
MetaSearch engine
A metasearch engine queries two or more
search engines at the same time. It sends
the results from the search engines back
to you.
Metasearch engines do not have their own
database or index web pages. They send
their queries to search engines. The
results from each search engine are
combined. Duplicates (pages that are the
same) are removed or merged. Pages are
sometimes ranked in order of importance.
Compiled by : S. Agarwal, Lecturer & Systems Incharge, St. Xavier's Computer Centre, Kolkata : [email protected]
Compiled by : S. Agarwal, Lecturer & Systems Incharge, St. Xavier's Computer Centre, Kolkata : [email protected]
Metasearch engines are good for finding information
quickly. They are best when keywords are used. You can
use metasearch engines to find out which search
engines have the information you want.
Metasearch engines do not return all the pages found.
They only return the top ten or so pages. This means you
can miss good pages using a metasearch engine.
When you use a metasearch engine, you tell it what
search engines to use. Metasearch engines use simple
queries. Examples of metasearch engines are
www.northerlight.comand
www.cyber411.com
Compiled by : S. Agarwal, Lecturer & Systems Incharge, St. Xavier's Computer Centre, Kolkata : [email protected]
Yellow Pages and Directories?
Yellow pages and directories are like telephone books.
They are web sites that have lists of pages about
companies, topics and products.
Keywords are placed in the directory. The keywords
are organized by topics. If a company has a web page
about "Computers", they send the address of the web
page to the directory. The address of the page is
added under the keyword "Computers".
The contents of the web page is NOT indexed by the
directory.
Examples of directories and yellow pages are
www.yahoo.com
www.infoseek.com
www.yellowpages.com
home.fares.net
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What is a search query?
A search query is what you want to find. It is
the words that you tell the search engine to
find.
If you are interested in fast cars, you ask a
search engine about "fast cars". Your search
query is "fast cars".
There are good ways to write a search query.
There are bad ways to write a search query.
You should use the most efficient method for
using a search engine.
Compiled by : S. Agarwal, Lecturer & Systems Incharge, St. Xavier's Computer Centre, Kolkata : [email protected]
You want to look for information about "Polar Bears". You ask the search
engine to find web pages about "Polar Bears". The search engine looks at all
the pages in its database. It makes a list of the pages about "Polar Bears".
The search engine sends the list of pages back to you. The list of pages is
called the results query.
The results query (list of resources returned by the search engine) is
not perfect. There are some good pages. There are some bad pages.
You must decide which pages have the information you want.
Compiled by : S. Agarwal, Lecturer & Systems Incharge, St. Xavier's Computer Centre, Kolkata : [email protected]
Using Search Engines
To use a search engine, you ask a question. You
use keywords.
A keyword is a word that is important. It is not
written more than once in a sentence.
When looking for keywords, do not use words like
in, and, the, what, how, why, a, there, when, me, I,
him, they, or, at, there, is, to, from, so
Compiled by : S. Agarwal, Lecturer & Systems Incharge, St. Xavier's Computer Centre, Kolkata : [email protected]
Consider the question
The keywords are
Consider the question
The keywords are
Consider the question
The keywords are
Compiled by : S. Agarwal, Lecturer & Systems Incharge, St. Xavier's Computer Centre, Kolkata : [email protected]
Basic Search Queries
A basic search query uses one or more keywords. The keywords
used affect the results. The better keywords used, the better the
results.
Rule 1
Use important words. Do not use words like
in, and, the, what, how, why, a, there, when, me, I, him, they, or, at,
there, is, to, from, so
Rule 2
Type all keywords in lowercase (small letters). The keywords Polar
and polar are not the same. The word Polar returns all pages with the
word Polar. The keyword polar returns all pages with Polar and polar.
Rule 3
Type a space between keywords
Rule 4
Do not use plurals in words. Use bear. Do not use bears. The
keyword bear returns all pages that have words beginning with bear
Rule 5
Spell words correctly.
Compiled by : S. Agarwal, Lecturer & Systems Incharge, St. Xavier's Computer Centre, Kolkata : [email protected]
Searching using a Phrase
A phrase is a short sentence. It begins with a double quote. It ends with a
double quote. This is a phrase.
"I was looking for Abdulla"
The search engine looks for the exact words on the web pages. You should
use a content-indexing search engine for best results (like altavista.com).
You use a phrase when you know the correct words. The order of the words
is important.
"I looking was for Abdulla" is NOT the same as "I was looking for Abdulla"
Searching by phrase looks for the exact occurrence of words. This example
searches for the phrase "Now is the time of our"
Spelling is very important if you use phrases!
Compiled by : S. Agarwal, Lecturer & Systems Incharge, St. Xavier's Computer Centre, Kolkata : [email protected]
Searching using Keywords
Keyword searching is popular when you have
keywords about the information you want.
We want to find out when christopher columbus
discovered America. We make up a list of
keywords to use. We could use "Columbus",
"America" and "discover".
The search engine will return all web pages that
have the words "Columbus", "America" and
"Discover".
Compiled by : S. Agarwal, Lecturer & Systems Incharge, St. Xavier's Computer Centre, Kolkata : [email protected]
Why are so many web pages found?
When you use keywords, the search engine
returns all pages containing every keyword. All
pages are returned that have the first keyword.
All pages are returned that have the second
keyword. All pages are returned that have the
third keyword.
Any page with the keyword "Columbus" is
returned. Any page with the keyword "discover"
is returned.
This is not what we want. We want pages that
have ALL three keywords. We need to change
the query to do this.
Compiled by : S. Agarwal, Lecturer & Systems Incharge, St. Xavier's Computer Centre, Kolkata : [email protected]
Keywords and the AND operator
In the previous example, any page containing any
of the keywords was returned. We want to say
any pages that have ALL the keywords.
The keywords are joined using AND. We write the
query like
This means search for pages that have
"Columbus" AND the keyword "America" AND
the keyword "discover". All three keywords must
be on the page.
Compiled by : S. Agarwal, Lecturer & Systems Incharge, St. Xavier's Computer Centre, Kolkata : [email protected]
Using the NOT operator
When you search using keywords, a lot of pages are returned. You
use the AND operator to reduce the number of pages.
Some of the pages returned are not good. They are not about what
you want.
You use the NOT operator to reduce the number of results. The
NOT operator removes pages.
Tip
Use lowercase in search phrases. Search engines return both
upper and lowercase results if you use lowercase. If you use
uppercase, only uppercase matches will be returned.
Compiled by : S. Agarwal, Lecturer & Systems Incharge, St. Xavier's Computer Centre, Kolkata : [email protected]
Advanced Search Queries
Advanced queries are used to sort the results, specify dates and
exclude more results. Various search engines have different options.
Using the + operator
The + operator works like the AND operator. The word or phrase
must occur in the pages returned by the search engine.
This query looks for all pages that have Columbus and America and
discover.
Compiled by : S. Agarwal, Lecturer & Systems Incharge, St. Xavier's Computer Centre, Kolkata : [email protected]
Using the - operator
The - operator works like the NOT operator. The
word or phrase must NOT be on any page
returned by the search engine.
This query looks for all pages that have
Columbus and America and discover, but NOT
discover, NOT museum and NOT sale.
Compiled by : S. Agarwal, Lecturer & Systems Incharge, St. Xavier's Computer Centre, Kolkata : [email protected]
Excluding domains
The Internet has a number of domains.
•Com commercial, companies
•Edu educational, colleges, universities, research and papers
•Net networks, internet companies
•Org organizations, local government
When you look for information, the search engine returns pages
from all domains.
You might not want to look on all domains. If you were doing
research and wanted to know what other people had written, you
would only use the edu domain.
In searching for information about Columbus, we decide to restrict
our search to the edu domain. This is because a lot of teachers
have written web pages about Columbus. The query looks like
Compiled by : S. Agarwal, Lecturer & Systems Incharge, St. Xavier's Computer Centre, Kolkata : [email protected]
end of show.
thank you.
Compiled by : S. Agarwal, Lecturer & Systems Incharge, St. Xavier's Computer Centre, Kolkata : [email protected]