Search Engines

Reyhaneh Salkhi

Outline

• What is a search engine?

• How do search engines work?

• Which search engines are most useful and efficient?

• How can you improve your search and find what you want easily?

• What is the difference between a search engine and a directory?

A computer program that can contact other network resources on the Internet ,search for specific information by keywords ,and report the results ;example is google.

What is a search engine?

A computer program that that searches several engines at once and integrates the findings of the various search engines to answer queries posted by the user.

Metasearch Engine

• Keyword Searching

• Refining Your Search

• Relevancy Ranking

• Meta tags

• Concept-based Searching

How search engines work?

Bots and spiders

Search engines use automated software programs called spiders or

bots to survey the Web and build their databases.

Keyword Search

• What is keyword exactly?

• The problem with keyword searching

• Indexing

Most sited offer two kinds of searching:

1.Basic

2.Advanced or refined

Refining your search

• to search on more than one word • to give more weight to one search term than the other • exclude terms • the form you want them to appear • the ability to use Boolean searching• the ability to search on phrases by putting them in

quotation marks • Capitalization: proper names • read the help files to know about the methods of different

search engines to refining queries

Advanced Search Refining Options

Meta Tags

• Meta tags in the beginning of the document

• Confliction on meta-tagging

• Meta tags in description

• Meta tags in description

• Meta tags in the title

• Spamdexing ( web authors using false and misleading keywords in the meta tags)

Result Ranking

• High up on the page• In headings • In BOLDFACE• In the URL• In the title (important)• In the description • In the generic keyword meta tags • In the link text for inbound links

Page Rank

That said a specific page’s relevance ranking for a specific query currently depends on three factors:

• Its relevance to the words and concepts in the query

• Its overall link popularity• Whether or not it is being penalized for

excessive search engine optimization (SEO)

PageRank Score

Every page on the internet has a minimum page rank score just for existing.

85% of this PageRank is passed along to pages that page links to.

So A page’s PageRank=

sum of the minimum value + all the PageRank passed to it via incoming links.

How sites get into the search engine?

The spiders crawl the entire Web , starting

from known pages and following all links , and also crawling pages that are hand submitted.

• People who have become famous.• People who post on the internet under their real names.• Academics and other people who publish articles and speak at

conferences. Professors also tend to have web pages.• Self-employed consultants and other people who have their own

business.• People active in community organizations.• Anybody with a career that causes them to get written about , cited

in articles or quoted in press.

Who is relatively easy to find on the web?

How to plan the best search strategy?

• Searching by means of subject directories.

• Searching by means of search engines:

1.Be Specific

2.Using The + Symbol to Add

3.Using The – Symbol to Subtract

4.Using Quotation Marks to Multiply

5.Combining Symbols

FAQ

1.Why do I need search engines ?

2.If its impossible to examine all the documents on the web how do search engines do it?

3.Which search engine is the biggest?

Different Search Engines Popularity

FAQ

4.What is the difference between a search engine and a directory like Yahoo!?

5.How do search engines work technically?

Questions?

Thank you!