Searching the Internet:
Recommended Sites and Search Techniques
This tutorial explores a variety of search tools to help you gain skills in conducting research on the Internet. 
This tutorial covers three basic types of tools:
Subject directories
Search engines, primarily first generation services that have been around for quite a while. More recent innovators are covered in Second Generation Searching on the Web.
The so-called "invisible" or "deep" Web, information accessible on the Web that is stored in databases. Search engines cannot or will not index this content, so it is "invisible" to them. Directories are a good place to find invisible Web content. In addition, there are collections devoted to listing database sites.
Why cover directories, engines, and the deep Web in one tutorial? A few reasons:
Many people use search engines without considering the usefulness of subject directories for their topics
The difference between these two types of tools is often poorly understood
Yahoo! is such a popular directory that more selective and higher quality directories are often overlooked
The two types of tools can complement each other in the research process
The amount of material on the deep Web is growing at a tremendous rate, so it is important to know what it is and how to access it
The lines are blurring between sites that offer either one resource or the other; for example, it is common to find directories and specialized databases (i.e., deep Web) at many search engine sites
Only a few examples of subject directories and search engines are covered in this tutorial.
For a more comprehensive list of subject directories, see: Internet Subject Directories
For a more comprehensive list of search engines, including those that give access to the deep Web, see: Internet Search Engines

Sites covered in this tutorial

Remember...

The Internet is a self-publishing medium. Your visits to subject directories and search engines will yield files with a wide range of quality from a variety of sources. Be sure to evaluate everything you encounter. For more information, see Evaluating Internet Resources.

Try out multiple sites when you are investigating a topic. Subject directories and search engines vary in their database contents, features, selectivity, and accuracy.

The world of subject directories and search engines is a highly volatile one. Don't be dismayed if you visit a site and discover that things have changed. This is par for the course. Many of these sites are commercial enterprises and competition is keen. When changes occur, they are often for the better as the service attempts to keep ahead of the pack. Enjoy the ride!

Quick Tip!

When should I use a subject directory?
When you have a broad topic or idea to research
When you want to see a list of sites on your topic often recommended and annotated by experts
When you want to retrieve a list of sites relevant to your topic, rather than numerous individual pages contained within these sites
When you want to search for the site title, annotation and (if available) assigned keywords to retrieve relevant material
When you want to avoid viewing low-content documents that often turn up on search engines
When should I use a search engine?
When you have a narrow or obscure topic or idea to research
When you are looking for a specific site
When you want to search the full text of millions of pages
When you want to retrieve a large number of documents on your topic
When you want to search for particular types of documents, file types, source locations, languages, date last modified, etc.
When you want to take advantage of newer retrieval technologies such as concept clustering, ranking by popularity, link ranking, and so on
When should I use the invisible Web?
When you want dynamically changing content such as the latest news, job postings, available airline flights, etc.
When you want to find information that is normally stored in a database, such as a phone book listing, listings of lawyers, doctors, etc. in a particular location, searchable collections of laws, and so on.

Here are sample topics and the tools you should use to retrieve information about them. This rule is not absolute, but should give you some general guidelines about how to approach subject directories and search engines as research tools.

Begin with a Subject Directory

Begin with a Search Engine
Disabilities Americans With Disabilities Act
Civil War Battle of Appomattox
Space exploration Mars Pathfinder
British literature Charles Dickens