Search Engines June 20, 2005 LIBS100 Linda Galloway

LIBS 100 Word of the Day A search engine that queries other search engines and then combines the results.

What is a search engine?? A program that searches documents for specified keywords and returns a list of the documents where the keywords were found.programkeywords

How Search Engines Work Spider or crawler –Visits page –Follows links on page to other pages –Sends terms to the holding area Index –Sorts through holding area –Stores significant words with a link to pages that have those words –Ignores words like “the” “and” “of” “to” Search engine software –Accepts your query term –Finds matching pages

Review Boolean Operators AND (+) locates records containing both terms. OR locates records containing either term NOT (–) locates records containing first term, but not the second Most of the time, operators MUST be capitalized

Major Search Engines Top Choices Crawler Based Google Yahoo Ask Jeeves (results from Teoma) Source:

Major Search Engines Good Choices Crawler Based AlltheWeb (editorial results from Yahoo) AOL Search (editorial results from Google) Hotbot (editorial results from Yahoo, Google, Teoma) Teoma

Subject Directories Human-powered Humans review, select, categorize web sites Changes to a site will not affect its listing on a directory

How Subject Directories Work Humans decide on a set of categories Humans review web sites (sometimes based on suggestions from users) Humans assign a site to a category Sometimes humans write actual content

Subject Directories Ranking No automated ranking algorithm Humans put categories in order Sites usually listed alphabetically Sponsored links

Yahoo Directory “Classic” Yahoo – uses humans to organize web sites into categories – –Yahoo directory only directory based search engine to get top rating Librarians Index to the Internet –

Subject Directories – Pros and Cons Pros –Human review/intervention –Sites are organized by topic –Sites can’t artificially inflate their ranking Cons –Very limited content –Only updated when humans find time

Popular Subject Directories Yahoo Directories ( About.com ( Librarian’s Index to the Internet ( Google Directories ( Infomine ( LookSmart (

So Which Do I Use? Search engine –You already have a very specific topic –You have a very new topic/need very latest info –You need quick facts Subject directory –You have a broad topic and want to narrow it down –You aren’t sure how to get more specific

Metasearch Engines A search engine that queries other search engines and then combines the results that are received from all. Searcher uses a combination of search engines at one time.

Metasearch Engines Disadvantages?? User cannot tailor search to each search engine. Dependant on other search engines’ technology.

Good Metasearch Engines Dogpile Vivisimo ( Hotbot Kartoo Mamma

Editorial Results (or Main Results) Results that are gathered by crawling or indexing web sites. Web masters pay a lot of attention to how their sites are listed. These are non-fee based listings

Paid Listings Web sites pay a fee to be among top hits for certain keywords. With some search engines, it is difficult to tell difference between editorial and paid listings. Paid hits are probably not the most relevant.

Search Engines Crawler-based Directory Metasearch

Results Listing Paid Editorial

Resources Rothenberger, Michelle. “Search Engines.” 6 Feb Staff. “Resources, INFS100.” Minneapolis Community and Technical College. 6 Feb Sullivan, Danny. “Search Features Chart.” Searchenginewatch.com 26 Oct Feb 2005.searchenginewatch.com/facts/article.php/ >.

Assignment 3 Due June 22, 2005 Handed out in class on Wednesday, June 15th You will perform a focused search using two search engines on your research topic

Assignment 3 Must Document Your Sources!!! Use MLA format Described on your Assignment Follows this format for web pages: Author’s Last Name, Authors First Name. “Title of Web Page.” Title of Complete Web Site, if Applicable. Date of Publication or last revision. Date accessed.

Like This! Sherman, Chris. “Metacrawlers and Metasearch Engines.” SearchEngineWatch.com 15 March Feb rticle.php/ >