Web search engines use special software programs called robots, spiders, bots, or crawlers to find Web pages and list (or index) all words within each one to make searching large quantities of pages faster. Indexes capture the largest amount of information on the Web, but no index lists everything on the Internet.
- Specialized web search engines – A tool that has a specialty, usually either a subject or format focus. It ignores the rest of the information on the web. Examples include Science.gov and TinEye Reverse Image Search.
- Metasearch engines – Tools that search multiple web search engines and gives you results from all of them. Some of these return the best results from the search engines they search. Examples include Dogpile and WebCrawler.
- Web directories – Tools created by editors or trained researchers who categorize or classify websites by subject. Directories are more selective than search engines. An example of this is Best of the Web.
- Lastly, there are search engines like DuckDuckGo or Startpage that keep your searches private such that you won’t see ads and other types of information that pop up on other web pages, social media, etc…
When to Use Them
Web Search Engines and related web search tools are helpful for locating background information, news especially if it’s recent, and public opinion. However, scholarly information is often not available through a regular web search. If you do find scholarly information through a web search engine, especially if you are off-campus, you may be asked for payment to access it. Don’t buy it! You should be able to request the resource through your library’s interlibrary loan (ILL) service.
Remember to follow the advice in Evaluating Sources to determine whether the information you locate online is suitable for your information needs.