Internet searching

Find reliable information on the web, including full electronic texts using the Library Catalogue, Search Engines, Directories and Gateways etc.

The two basic approaches to searching the Web are search engines and subject directories.

Search engines are huge databases of web page files that have been assembled automatically by machine.

There are two types of search engines:

Individual search engines compile their own searchable databases on the web.

Metasearchers do not compile databases. Instead, they search the databases of multiple sets of individual engines

How do search engines work?

Search engines compile their databases by employing "spiders" or "robots" ("bots") to crawl through web space from link to link, identifying and perusing pages. Sites with no links to other pages may be missed by spiders altogether. Once the spiders get to a web site, they typically index most of the words on the publicly available pages at the site. Web page owners may submit their URLs to search engines for "crawling" and eventual inclusion in their databases.

Whenever you search the web using a search engine, you're asking the engine to scan its index of sites and match your keywords and phrases with those in the texts of documents within the engine's database.

It is important to remember that when you are using a search engine, you are NOT searching the entire Web, as it exists at this moment. You are actually searching a portion of the web, captured in a fixed index created at an earlier date.
How much earlier? It's hard to say. Spiders regularly return to the web pages they index to look for changes. When changes occur, the index is updated to reflect the new information. However, the process of updating can take a while, depending upon how often the spiders make their rounds and then, how promptly the information they gather is added to the index. Until a page has been both "spidered" AND "indexed," you won't be able to access the new information.

When do you use search engines?

Search engines are best at finding unique keywords, phrases, quotes, and information buried in the full-text of web pages. Because they index word by word, search engines are also useful in retrieving tons of documents. If you want a wide range of responses to specific queries, use a search engine.

EXAMPLES OF INDIVIDUAL SEARCH ENGINES:

• All the Web (Fast)
• All the Web (Fast) Advanced Search Page
• AltaVista
• AltaVista Advanced Search Page
• Google
• Google Advanced Search Page

Meta search tools

The growth in the number of search engines has led to the creation of "meta" search tools, often referred to as multi-threaded search engines. These search engines allow the user to search multiple databases simultaneously, via a single interface. While they do not offer the same level of control over the search interface and search logic, as do individual search engines, most of the multi-threaded engines are very fast. Recently, the capabilities of meta-tools have been improved to include such useful features as the ability to sort results by site, by type of resource, or by domain, the ability to select which search engines to include, and the ability to modify results. These modifications have greatly increased the effectiveness and utility of the meta-tools.

Popular multi-threaded search engines include:

• Metacrawler (http://www.metacrawler.com)
• Ixquick (http://www.ixquick.com)
• SurfWax (http://www.surfwax.com
• Dogpile (http://www.dogpile.com)
• ProFusion (http://www.profusion.com)

Subject-specific search engines do not attempt to index the entire Web. Instead, they focus on searching for Web sites or pages within a defined subject area, geographical area, or type of resource. Because these search engines aim for depth of coverage within a single area, rather than breadth of coverage across subjects, they are often able to index documents that are not included even in the largest search engine databases. For this reason, they offer a useful starting point for certain searches. The table below lists some of the subject-specific search engines by category. For a more comprehensive list of subject-specific search engines, see one of the following directories of search tools:

• Beaucoup! (http://www.beaucoup.com)
• Search Engine Colossus (http://www.searchenginecolossus.com)
• Searchengines.com (http://www.searchengines.com/)

Table of selected subject-specific search engines and a few subject directories

When to search; quality checks and criticism of sources
Evaluating the quality of information provided on a Web site involves more than determining its authenticity. An author may write with genuine passionate belief in that which he says, but the facts may not support his contention. Examine, for example, this document, alleging that aspartame causes multiple sclerosis. While inaccurate, and perhaps irresponsible, it is not necessarily a fake.

Before you rely on information, you should:
Determine its origin.
Discover the author AND the publisher.
Ascertain the author and publisher's credentials.
Discover the date of the writing. This gives the information historical context.
Verify it. Find another reputable source that provides similar information.

Source Selection Tip:
Try to select sources that offer as much of the following information as possible:
Author's Title or Position
Author's Organizational Affiliation
Date of Page Creation or Version
Author's Contact Information
Some of the Indicators of Information Quality