Library
Various types of "tools" are available on the Internet to help you find the information you need on specific topics. The different types of tools are described below, with links to specific examples of each different type and to instructions on how to use many of the specific tools. Some of the sites that are listed include more than one type of tool (e.g., sites such as Yahoo! or Alta Vista include both a subject directory and a search engine at one site.)
Also be sure to read the general tips for how to combine search words in Web search engines included at the end of this page. This will help you understand how to develop more effective searches using any of the search tools discussed.
Internet subject directories are general subject indexes to all types of Web sites and other Internet documents. Each site included in a directory is listed under one or more subject categories, as determined by the directory's indexers. The listing for each site usually includes a brief description of the site.
Directories are often a good place to start looking for information on relatively general subjects and to get an overview of what is available on the Internet in almost any subject area.
Directories can usually be used in two basic ways:
There is wide variation in the number and quality of sites included in different directories, as well as in the amount of descriptive information provided for the listed sites in the various directories. Some directories, such as Yahoo! or Excite, try to be as comprehensive as possible, with very extensive listings.
Examples of large Internet directories:
One disadvantage of these large directories is that they usually do little, if any, review of the quality of the sites they list so you often cannot easily find which are the best sites in a particular subject area.
Some directories only list sites that they have selected as the best sites in various different subject areas. Some of these selective directories, that have been developed by librarians, professors or other subject experts, focus on more academic information and are sometimes referred to as "virtual libraries" or "webliographies". These selective directories often provide many links to other specialized intermediary sites which, in turn, provide links or search engines leading to quality documents in a particular subject area. These intermediary sites include:
Examples of selective directories:
Subject guides are sites that provide links (often with excellent annotations) to high quality sites in a specific subject area. Some examples of subject guides in higher education discipline areas:
While directories organize web sites according to subject categories, Web search engines are search tools that allow users to search for any word in almost any site on the Internet. Search engines are useful for searching for very specific information, but they are not the best tools for finding sites on broader topics (directories should be used to find sites on more general subject areas.) Web sites that are included in search engines are not selected, organized or previewed by any humans. Search engines' indexes are created entirely by computer programs (called spiders or robots) that continuously scan sites throughout the Internet to add to or update their lists of web sites.
Since search engines' indexes of web sites are both huge and have no subject organization at all, it is very important to think carefully about what search words to use and to be aware of the different search features available before performing a search. (See the Tips for Boolean Searching on the Web and the link to the Search Tools' Features Chart listed below.) To use search engines effectively, it is usually best to combine several search words related to a search topic using the search strategy skills discussed in the Search Strategy section of Skyline Library's "Research Assistant".
Examples of Web search engines:
Media search are search engines that search specifically for web images and audio and video files. Examples of media search engines:
Meta-search engines are special search tools that allow you to search multiple search engines at one time. Since each search engine includes a different set of sites, many search experts recommend using meta-search engines in order to perform the most extensive search possible. Although the early versions of these meta-search tools were sometimes very slow, their performance has improved considerably over the past few years. Because they search numerous search engines with a single search statement, they generally cannot include as many advanced search features as do individual search engines.
Examples of meta-search engines:
One major limitation of all the web search engines and meta-search engines is they cannot search information that is available within thousands of specialized databases that are available on the Web. These databases include all types of periodical databases (databases that index anywhere from one to hundreds of different magazines, journals and newspapers by subject and may include abstracts or the complete text of articles), government databases (including a wide range of information from census data to legal codes to all types of public records), media databases, including radio and television reports and databases of all types of non-profit and commercial organizations. These databases have their own internal data and their own internal search engines.
Examples of databases available on the Web:
To find specialized Web databases in many different subject areas, you can try using one of the subject directories or "virtual libraries" listed above. When you search for databases in a subject directory or virtual library, try searching for a subject that is somewhat broader than your specific topic and also include the word "database" in the search.
There are also some sites that list Web databases in all subject areas. Lists of searchable databases on the Web are available at the following sites:
Use these sites to find databases or search engines on the general subject of your research. Once you find a database or search engine on your general subject area, you can use that subject-based search tool to search for more specific information related to your topic.
Search engines on the Web--whether general web search engines or
local search engines for particular databases--often use special
search features for combining multiple search words in a single
search. These special features are especially important when your
search topic includes multiple concepts. See "Planning
a Search Strategy" for an explanation of how to divide a research
topic into concepts and organize multiple search words into an
effective "search strategy". (Most web search engines typically
implement these features differently than traditional periodical
databases, such as the InfoTrac Searchbank databases). The tips below
describe general characteristics common to many Web search engines,
but there is no common standard--each search engine has
variations.
*Before using any search engine, you should always check
the instructions, help screens or other documentation that
explain the specific features of that engine.
AND: many Web search engines use the + sign (often called the "require" sign) in front of words that must be included in the search, e.g., + immigration +economy is often used instead of immigration AND economy
OR: many Web search engines assume a space = OR, e.g., economy business is often the same as economy OR business
Phrases (consecutive search words): quotes must be placed around phrases in most search engines, e.g., "illegal immigration"
Truncation: only some Web search engines allow truncation; those that do usually use * for truncation, e.g., econom* finds- economy, economic, economics, economist, etc.
Search sets: Web search engines generally do not create
sets for search results; instead they allow the use of parentheses
(as in algebraic equations) to designate which logical operators are
to be carried out first.
For example, in the following search:
("illegal immigra*" OR "illegal aliens" OR "undocumented workers")
AND econom*
a search engine would first search for: "illegal immigra*" OR
"illegal aliens" OR "undocumented workers" and the results of
these ORed terms would then be ANDed with econom*
"Relevance ranking": a programming method that attempts to rank search results based on various factors. Different search engines use different ranking systems. Searched documents are ranked on such factors as:
Finding key words on a Web page: When you view pages that have been found by a search engine, you can find where the search terms are located on the page by using the Find command on the Netscape "Edit" pull-down menu.
See the: Search Tools' Features Chart for a list of search features for many of the major Web directories and search engines; or the Quick Guide comparing the basic features of the major search engines. (Both of these pages are from the "InfoPeople" Project)
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