An Overview of Search Tools

Most online "searching tools" can be categorized as either a subject tree, search engine, or virtual library. In order to be successful in your searches, it is important to always know which kind of online resource you are using. This page provides a brief overview to explain the differences between these classes of online tools.

Russ Portrait

Types of online Search tools:

Subject Trees:
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Subject Tree - Key Features

  • Main menu presents a list of menu choices
  • Web pages are created manually
  • Web sites must typically "announce" or "register" themselves to appear within the directory.
  • Links are grouped together on web pages based on a criteria such as subject (yahoo) or geography (citynet)
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A subject tree is a subject-oriented index to many thousands of Internet sites. You begin at a high level of subject area, and usually browse your way down to topics and sub-topics.

From an initial menu, you must decide "where" your desired subject might be listed. As you select menu items, you will notice that you are going "deeper" down a menu hierarchy. (look at the URL’s in the location window) Eventually, you will reach a "bottom page" in the hierarchy. The bottom web page contains the hyperlinks that will take you away from the subject tree web site to the specific web sites containing your desired subject.

A Subject tree may offer a "search" option. Recognize that this is not a "search of the Internet", but rather a keyword search of the web pages contained within the subject tree. Remember that most subject tree web pages contain only the words: "name of subject", "names of subtopics", "names sub-subtopics", "brief description of XYZ website".  Therefore keep your search terms at a subject tree at the appropriate level of detail (i.e. search for a subject)

Note that most subject trees are manually built, usually from user submissions. If someone creates a web site, and they want to be "found", they should be sure to announce themselves to subject trees such as Yahoo.

One of the oldest and most popular subject trees is Yahoo. It’s extensive set of topic pages will often lead you to dozens of online resources related to a specific topic. Main subject categories are indicated in the larger fonts, with popular sub-topics also included in the smaller font. As a popular commercial site, The Yahoo corporation also offers additional online resources such as maps, phone books, and stock quotes.

Search Engines:

Search Engines- Key Features

  • Robot explores Internet via discovered hyperlinks
  • Full text copy of web pages often retrieved
  • Massive database is collected/indexed
  • Key word searches may yield many thousands of "hits"

Search engines are usually characterized by very large indexed databases, which contain pointers to millions of URL’s. Search engines have two main functions that distinguish them from each other.

Building the index. Many Search engines develop their vast databases by using a software application to automate the exploration of the Internet. These applications (known as robots, spiders, and crawlers) visit web pages, copies them into a local database, and then explores all the links referenced in the freshly copied page. In this manner, the search engine may eventually discover a high percentage of web pages so long as they are pointed to from someone else’s page. (You can also "invite" the search engine to explore your site)

The Search Interface. As the web page information harvested, it is indexed and made available to the Internet through a user interface. Each Search engine may contain different options and parameters that can be used to search its database. In general, you are performing a full keyword search against the entire text from millions of web pages. Search engines also rank the search results in some order based on a scoring criteria. If you use a search engine frequently, it pays to read the "about this search engine" or "advanced Search" options to learn more about how the search engine is interpreting your queries. Note: Most search engines use "or" as the logical operator in a multi-word search. You may want to explore the online help to see how to focus your search queries. Also be careful to avoid using common words which may "dilute" your search results.

Alta Vista is a very powerful Search engine, which offers a wealth of search parameter options. Besides containing an index of millions of web pages, Alta Vista Also has a searchable index of the usenet News messages. The default interface for Alta Vista is the simple query. If you use Alta Vista on a regular basis, you are strongly encouraged to look at the information contained in their online help. Most Search engines like Alta Vista will respond with a large number of "hits" that match your search string. Fortunately, These search results are "scored" and ranked based on how prominently/frequently the key words appear on the web page.

Each hit includes a hyperlink to the web page and some portion of the web page’s text. You should take the time to look at the URL’s to help decide which web page might meet your needs before you attempt to access the page. After looking at these top these top ten results, you can then ask for the next batch of ten , and "work" your way through all the suggested web pages.

Virtual Libraries:

Virtual Libraries- Key Features

  • Usually focused on a specific subject area
  • Often developed by “experts” in that field

There is an abundance of online resources and a variety of tools to seek out information. Unfortunately, there are few of us who can afford to dedicate "their entire life" to the task of constantly searching the Internet for the latest information in a particular subject. Fortunately, there are other Internet users who are able to invest such time into research their (your) topic. Probably the single best way to thoroughly cover a topic, is to discover a Virtual Library for that topic. Virtual Libraries are subject-specific indices that are created (and maintained) by someone who really cares about that topic.

Tip: The best way to discover a "Virtual Library":

  1. Go to a good subject tree such as Yahoo
    1. Browse down a couple of layers to the subject of your choice
    2. Usually, there is an "indices" or "FAQ" listing for each subject area (For example look at this page on Security from Yahoo, and try the indices link at the top of the page)
    3. Go and visit each of the indices for your subject
    4. Make a bookmark of the best ones
    5. For example Yahoo's security indices links towards COAST Laboratory/Spaf's Hotlist . Check out this site and see how long it would have taken you to compile such an extensive listing
  2. A list of VL’s are linked together at “the” WWW Virtual Library . The virtual library has the look and feel of Yahoo, but the individual subject areas are distributed and maintained by subject experts.
  3. Always watch for sites labeled: “John Doe’s Ultimate guide to widgets” or “The widget meta-site”
  4. Ask other users. Within any subject area there, is often 2-3 sites that everyone recognizes as being the best.
Discussion: How to choose the right tool

By now you are realizing just how vast the information can be on the Internet. Search engines like Alta vista can quickly provide you with "many" choices. A common question at this point is; "know that we know about Alta Vista, why would we ever use Yahoo?" Yahoo is still quite useful when:

For example, to find out about computer security, Yahoo might be your best starting place (computers -> security) Once there, you might learn some of the terminology (i.e. kerberos, pgp, DES) These specific words can eventually be used at a search engines such as Alta Vista.

Search engines are best used when you have very specific information you are seeking. Since Search engines do provide different results from each other, feel free to experiment and try different ones. For more information, see

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