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Internet Research
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| Sana | 28.03.2024 | | Hajmi | 0.64 Mb. | | #179700 |
Bog'liq 2-Search Engines (1) “FIZIKA ” FANIDAN TA’LIM TEXNOLOGIYASI, DAROMADLARNI BOSHQARISH BO\'YICHA XALQARO HISOBOT STANDARTLARI, ozbekiston tarixi fanidan test - Search Engines & Subject Directories
Search engines - Search engines are the means by which most people search the Web.
- Common examples are Google, Altavista, Direct Hit.
- 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 “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 gathered and indexed by word.
- These databases can be huge, with millions of links.
- Using the keywords you give it, a search engine then searches its own current index.
- 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.” 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 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:
- 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
- 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 the idea a step further with subject guides for selected topics.
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 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 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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