MAKERERE UNIVERSITY

JINJA CAMPUS

PROGRAMME NAME: BACHELOR OF INFORMATION TECHNOLOGY (MAK-JINJA)

COURSE CODE: JBI - (Evening)

COURSE UNIT: BIT 2111 Web Systems and Technologies I

LECTURER: BITWIRE GEORGE ALBERT

TASK: ASSIGNMENT 01:In about one page,“Describe How Internet Search Engines Work”

DUE DATE: Friday, 22nd August, 2014.

Name REGISTRATION №: STUDENT №

Mukalele Rogers 13/U/21067/EVE 213024492

SIGNATURE: …………………………………………………………………………..

P.T.O.

INTRODUCTION web search engine is a system that is designed to search for information on the World Wide Web and FTP servers and return

a line of results (hits), usually in form of a mix of links to web pages, images, and other types of files. Web search engines work by storing information about many web pages, which they retrieve by a spider (an automated Web crawler) which follows every link on the web pages.

A

The search engine analyzes the contents of web pages and determines words to store in an index database. Zone

Words can be extracted from the titles, page content, headings (eg <H1>, <H2>, etc or special fields called meta tags.

When a user enters a query into a search engine (typically by using keywords), the engine examines its index database and provides a listing of best-matching web pages according to its criteria, usually with a short summary containing the document's title and sometimes parts of the text.

ILLUSTRATION

SPECIAL SEARCH ENGINE TECHNIQUES1. Some search engines, store all or part of the source page

(referred to as a cache) as well as information about the web pages. This cached page always holds the actual search text since it is the one that was actually indexed, so it can be very useful when the content of the current page has been updated and the search terms are no longer in it or is unavailable.

2. Some search engines allow users to search by date by clicking "Show search tools" in the leftmost column of the initial search results page, and then selecting the desired date range.

3. Most search engines support the use of the Boolean operators AND, OR and NOT to further specify and refine the search queries.

4. The engine looks for the words or phrases exactly as entered. Some search engines provide an advanced feature called proximity search, which allows users to define the distance between keywords.

5. There is also concept-based searching where the research involves using statistical analysis on pages containing the words or phrases you search for.

6. Natural language queries, supported by some search engines such as ask.com, allow the users to type a question in the same form one would ask it to a human.

7. The usefulness of a search engine depends on the relevance of the result set it gives back. While there may be millions of web pages that include a particular word or phrase, some pages may be more relevant, popular, or authoritative than others.

8. (a) Most search engines employ methods to rank the results to provide the "best" results first. Most Web search engines are commercial ventures supported by advertising revenue and thus some of them allow advertisers to have their listings ranked higher in search results for a fee. (b) Search engines that do not accept money for their search results make money by running search related ads alongside the regular search engine results. The search engines make money every time someone clicks on one of these ads.

2END.