What Are Search Engines and Web Directories?

Search engines are huge databases of web pages that have been assembled automatically by machines. There are two types of search engines: individual and meta. Web directories are databases that have been created by humans and are used to organize web sites into subject categories.

  • Individual Search Engines compile their own searchable databases, using "spiders" or "robots" that read the web pages and all other links within the web site. Spiders return to these sites periodically to note any changes and to record the changes in the database. When you use a search engine, you will retrieve "hits" based on the web sites contained in that search engine's database. Examples include: Alta Vista, Excite, Google, HotBot, Lycos
  • Meta-Search Engines do not compile databases. Instead, they search various individual search engines simultaneously on behalf of the user, and retrieve "hits" from each of those databases. Examples include: DogPile, Go2Net, Metacrawler, WebCrawler
  • Web Directory databases depend upon people for their content. Web site creators submit site descriptions to the directory; editors then review and select which sites will be included in the directory. Individual web sites are filed within searchable subject categories. In general, directory databases tend to be smaller than search engine databases. Examples include: Librarians Index to the Internet, Open Directory Project, Yahoo

Pros & Cons of Using Search Engines and Web Directories

  • Individual Search Engines:
    provide access to a large portion of available web pages and are the best way to search for information on the Web.
    Con:  Because search engines index so many words in their databases, they can easily retrieve hundreds of thousands of irrelevant returns from simple searches.
  • Meta-Search Engines:
    are very fast and are good to use if for simple simples and quick topic over-views.
    Con: Because they search so quickly, meta-search engines retrieve only about 10% of the results available from other search engines.
  • Web Directories
    are organized into browsable subject categories that can deliver higher quality, less irrelevant returns than search engines.
    Con:  Because web directories don't compile their own databases, they can often point to web pages that have content changes, have moved or no longer exist.

When To Use Search Engines and Web Directories

Because search engines and web directories search for information differently, choose an engine or directory that will be suit your searching needs:

Individual Search Engines:   Best to use when you are looking for specific web sites or specific information. For best results:

Always search more than one search engine for information- no single search can retrieve every piece of web information related to a topic
Never assume that the first web site retrieved is the best one- always evaluate the site "hits" that are received
If you don't find the information that you are looking for within the first 25 "hits", modify your search terms and search again
Remember, individual search engines do not search the entire Web, they search their own databases of compiled web pages.

Meta-Search Engines: 

Keep your searches simple: use only a few keywords, always put quotation marks around phrases
Be aware of which other search engines your meta-search engine is using.
Remember, meta-search engines send your keywords to other search engines, then retrieve a combined result of "hits" from those other search engines- they do not search their own web site databases for information.

Web Directories: 

Subject category searches are recommended- if you do a keyword search, take note of the subject categories that your search retrieves
Directory editors decide which sites will be included into each subject category- be aware that not all web sites will be included
Remember, because web directories are built and maintained by people, they contain far less web sites than traditional search engines do.