Internet Research Search Engines Subject Directories Search engines
![Internet Research Search Engines & Subject Directories Internet Research Search Engines & Subject Directories](https://slidetodoc.com/presentation_image_h/c275f2cf5e2a22da921f5c7c5149a364/image-1.jpg)
Internet Research Search Engines & Subject Directories
![Search engines • Search engines are the means by which most people search the Search engines • Search engines are the means by which most people search the](http://slidetodoc.com/presentation_image_h/c275f2cf5e2a22da921f5c7c5149a364/image-2.jpg)
Search engines • Search engines are the means by which most people search the Web. • Common examples are Google, Altavista, Direct Hit.
![Yet they don’t search the Internet • Yet a search engine does not actually Yet they don’t search the Internet • Yet a search engine does not actually](http://slidetodoc.com/presentation_image_h/c275f2cf5e2a22da921f5c7c5149a364/image-3.jpg)
Yet they don’t search the Internet • Yet a search engine does not actually search the Web during your search. • A search engine searches itself. • It’s a three-step process.
![1) Bots index words • Search engines continually send out hundreds of “robots” or 1) Bots index words • Search engines continually send out hundreds of “robots” or](http://slidetodoc.com/presentation_image_h/c275f2cf5e2a22da921f5c7c5149a364/image-4.jpg)
1) Bots index words • Search engines continually send out hundreds of “robots” or “bots” (or “spiders” or “crawlers” ) • Bots visit web sites, read word by word, and then index those words.
![2) A database is created • A huge database of Web sites thus is 2) A database is created • A huge database of Web sites thus is](http://slidetodoc.com/presentation_image_h/c275f2cf5e2a22da921f5c7c5149a364/image-5.jpg)
2) A database is created • A huge database of Web sites thus is gathered and indexed by word. • These databases can be huge, with millions of links.
![3) The Interface gives you access • Using the keywords you give it, a 3) The Interface gives you access • Using the keywords you give it, a](http://slidetodoc.com/presentation_image_h/c275f2cf5e2a22da921f5c7c5149a364/image-6.jpg)
3) The Interface gives you access • Using the keywords you give it, a search engine then searches its own current index.
![Interfaces are based on rankings • Search engines return results based on a ranking Interfaces are based on rankings • Search engines return results based on a ranking](http://slidetodoc.com/presentation_image_h/c275f2cf5e2a22da921f5c7c5149a364/image-7.jpg)
Interfaces are based on rankings • Search engines return results based on a ranking system. • Ranking is the order that files are listed when they are retrieved.
![The ranking system is secret • These systems are proprietary and often “secret. ” The ranking system is secret • These systems are proprietary and often “secret. ”](http://slidetodoc.com/presentation_image_h/c275f2cf5e2a22da921f5c7c5149a364/image-8.jpg)
The ranking system is secret • These systems are proprietary and often “secret. ” In general: • Altavista ranks web pages higher if your search terms are found in the first few words of the page • Google ranks by document “popularity” with other similar searches • Direct Hit ranks by the length of time other users spent at the site
![Not even half the Web • With all of this software and sophistication, even Not even half the Web • With all of this software and sophistication, even](http://slidetodoc.com/presentation_image_h/c275f2cf5e2a22da921f5c7c5149a364/image-9.jpg)
Not even half the Web • With all of this software and sophistication, even the best search engines cover only 40 -50% of the Web. • And they miss much else on the Internet.
![Bots hit and miss Bots miss: n n n XML pages, pdf files Dynamically Bots hit and miss Bots miss: n n n XML pages, pdf files Dynamically](http://slidetodoc.com/presentation_image_h/c275f2cf5e2a22da921f5c7c5149a364/image-10.jpg)
Bots hit and miss Bots miss: n n n XML pages, pdf files Dynamically created HTML pages Frames-based pages New pages or recent updated text Some say the Invisible Web is 500 times larger than Web
![Subject Directories • A subject directory is also a database of web sites and Subject Directories • A subject directory is also a database of web sites and](http://slidetodoc.com/presentation_image_h/c275f2cf5e2a22da921f5c7c5149a364/image-11.jpg)
Subject Directories • A subject directory is also a database of web sites and references. • But a subject directory is organized not by keywords but by category or subject.
![Yahoo! • Yahoo! Is the most popular subject directory. • www. about. com takes Yahoo! • Yahoo! Is the most popular subject directory. • www. about. com takes](http://slidetodoc.com/presentation_image_h/c275f2cf5e2a22da921f5c7c5149a364/image-12.jpg)
Yahoo! • Yahoo! Is the most popular subject directory. • www. about. com takes the idea a step further with subject guides for selected topics.
![Subjects are organized by people. • Information is selected, organized and cataloged by a Subjects are organized by people. • Information is selected, organized and cataloged by a](http://slidetodoc.com/presentation_image_h/c275f2cf5e2a22da921f5c7c5149a364/image-13.jpg)
Subjects are organized by people. • Information is selected, organized and cataloged by a person, not software. • You can usually be more assured that the search results will make sense.
![You get an index of sites. • Subject directories will not often provide you You get an index of sites. • Subject directories will not often provide you](http://slidetodoc.com/presentation_image_h/c275f2cf5e2a22da921f5c7c5149a364/image-14.jpg)
You get an index of sites. • Subject directories will not often provide you with ranked web sites. • Instead, you will get a broad index related to your topic, divided further by subheadings.
![Use for early searching. • Use a subject directory early in your search process Use for early searching. • Use a subject directory early in your search process](http://slidetodoc.com/presentation_image_h/c275f2cf5e2a22da921f5c7c5149a364/image-15.jpg)
Use for early searching. • Use a subject directory early in your search process to learn about your subject. • You will get fewer links of higher quality. • When you get more specific questions, you should use a search engine.
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