An overview of Internet search tools
Unlike a single library or a single database, the Internet is a hodge-podge of sources of information without a central, unified catalog to access the information. After all, the Internet is a loosely-connected worldwide network of computers and computer networks (INTERconnectedNETworks).
Because of this scattered, disorganized nature of the Internet as a repository of information, search tools have been devised in an attempt to rein in its contents. The vastness and constant explosive growth of the Internet makes it impossible for any single tool to keep up with it. That's why hundreds of search tools have been created to help satisfy every conceivable type of search need.
Generically speaking, search tools are lumped together and most commonly referred to as search engines. In the strictest sense, a search engine is defined from its original meaning as a robotic spider that crawls the Internet and gathers websites into a searchable database. What are broadly referred to as search eninges are actually search engines as well as various kinds of subject directories and guides that cover the entire breadth of the Internet. These search tools are broken down functionally as follows.
General search engines
Subject directories
Portals
Vortals
Meta search engines
Specialized search engines
Reference tools
News searchers
Bots
Periodical tools
Image and multimedia search tools
Kids search engines
Invisible Web search tools
Knowledge networking tools
Web rings
Best-of-the-Web guides
Search engine guides
General search engines
General search engines, using automated robotic spiders that crawl the Internet to index websites, are the single most powerful search
ools available to singly search the largest number of websites. A general search engine is the first choice for many experienced searchers and in most cases will be the only tool needed for most searches. They are the all-purpose tool to cover all subjects and all kinds of websites.
A search is made in a general search engine by entering keywords in a search text box. The search engine then searches its database of collected sites by matching the keywords with the words contained in its collection of Web pages. Pages found that have the search words are hits. The hits with the most relevancy are listed first in the listings of search results. Relevancy is how strongly the search words match the words in the page. This is calculated mathematically through formulas. A greater frequency of search words in the pages and presence of the words in headings and at or near the top of the page creates higher scores of relevancy.
The top-rated search engine is Google (www.google.com) and also the largest search engine, with coverage of over three billion sites. In side-by-side comparisons of performance, Google has consistently outperformed all other search engines in remarkable fashion. Google pioneered the addition of link analysis to the calculation of relevancy. Link anlysis has the uncanny ability to locate the best Web pages by measuring how many quality Web pages link to a particular website.
No single search engine, no matter how large, can keep up with the unceasing explosion of the Web. Even the best search engine may not find everything you need all the time. If, on occasion, Google doesn't find what you are looking for, you can try other search engines and tools. Here are the other top general search engines, listed in order of size of coverage of the Web:
Subject directories
Web subject directories offer a smaller, more selective collection of websites that are picked by human editors instead of by automated spiders. Although smaller in size than the database of sites held by a search engine, an advantage of directories is a higher concentration of quality sites, because they are chosen directly by humans. The sites listed in a directory search are annotated and reviewed with editors' descriptions, and represent the top-rated sites within their subject categories. In addition to searching by keywords in a textbox, topics in a directory can be selected by browsing through hierarchical listings of subject categories organized as a subject tree. A topic is located by clicking through subject listings, burrowing deeper with each click into narrower topics until the appropriate one is found.
There are two types of subject directories: popular/commercial and academic/professional. The best-known--and also the oldest-- directory is Yahoo! It is also arguably the world's most used search tool. Another major popular subject directory that is noteworthy is that of Google.
Google uses the Open Directory Project for its directory, using its link analysis system to optimize searching. The Google directory is much larger than Yahoo!, and, in fact, the Open Directory Project database it uses is the largest directory on the Web. A Google search taps simultaneously into the Google search engine as well as into its Open Directory Project directory. This pairing of search engine and subject directory as one combined tool is called a hybrid..
The academic/professional directories have been created by librarians and are not for profit, but are maintained as a service for scholarly searchers.
There has been a shakedown of directories, and the remaining core groups include the following.
POPULAR/COMMERCIAL DIRECTORIES
ACADEMIC/SCHOLARLY DIRECTORIES
University of Delaware Subject Guides
Portals
(under construction)
Top
