Search Engines

1) Introduction
2) Web Directories
3) Search Engines
4) Understanding a URL

5) Five Types of Webpages
6) Evaluation Criteria
7) Quiz

While subject directories organize Web sites according to subject categories, Web search engines allow users to search for any word in the millions of sites that they index. With the phenomenal success of Google, search engines have replaced Web directories as most users' preferred means of finding information on the Web.  Nowadays, when most of us want a piece of information, particularly a fact, we "Google" it. 

That said, Web directories should not be overlooked in the research process.  One of the advantages of directories like the Librarians' Internet Index is that they search a smaller subset of the Web, pre-screened by human beings. Search engines do not use people to select, organize or preview Web sites; they rely on computer programs called spiders (or robots) to continuously scan the Internet looking for new sites and updates to add to the index.

Since search engines' indexes of Web sites are huge and have no subject organization, it is important to think carefully about what words to use and to be aware of the various search features available before performing a search. Look for the "Search Help," "Search Tips," or other pages that explain the features of the particular search engine you are using. To use search engines effectively, it is usually best to either have very precise search words or to combine several words related to a topic. Try a variety of search terms (brainstorm synonyms and related words and phrases) to expand your results.

Metasearch engines, such as Dogpile and Clusty, go one step beyond search engines: They aggregate the results of multiple search engines.

Listed below are features and capabilities common to many Web search engines. Keep in mind that these features may not work the same way -- or even be available -- in every search engine.

AND. Some search engines, such as Google, interpret a typed space as a Boolean AND. For example, immigration economy would be read as immigration AND economy.

OR.  Other Web search engines assume that a typed space means OR. For example, economy business would be the same as economy OR business.

Phrases. Quotation marks (" ") must be placed around phrases (consecutive search terms) in many search engines. For example: "illegal immigration" can be entered to find those two words next to each other as a phrase.

Truncation. Only some Web search engines allow for truncation. Those that do usually use the asterisk (*) to truncate a search term. For example, econom* finds: economy, economic, economics, economist, etc.

Relevance ranking. This is a programming method that attempts to rank search results based on various factors. Different search engines use different ranking systems. Documents returned from a search can be ranked by such factors as:

  • frequency of search words in the document
  • words found in the title or near the beginning of the document
  • search words found close to one another

Google takes into account the popularity of a page when ranking results.  In other words, a page that has been linked to by a lot of other pages will come up higher on the results list.

Finding key words on a Web page. When you view lengthy Web pages, it is sometimes hard to see where your search terms are located. You can find exactly where a specific word is located on the page by using the Find in Page command.  This is often in the Web browser's menu (for example under Edit/Find in Microsoft Internet Explorer), or can be activated by typing Control + F on your keyboard.

Recommended Search and Metasearch Engines:

Adapted from:
Skyline College, LSCI 100: Introduction to Information Resources.