Web search engines use special software programs (called robots, spiders, 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.

Commonly used search engines include Google ⧉ (https://www.google.com) and Bing ⧉ (http://www.bing.com).

In addition to search engines, there are also:

• 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 ⧉ (http://www.science.gov/) and TinEye Reverse Image Search ⧉ (https://www.tineye.com).
• 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 ⧉ (http://www.dogpile.com) and WebCrawler ⧉ (https://www.webcrawler.com).
• Web directories – Tools created by editors or trained researchers who categorize or classify web sites by subject. Directories are more selective than search engines. An example is the Directory of Open Access Journals ⧉ (https://doaj.org/).

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. Your institution can usually get articles for you through interlibrary loan, without the need for you to pay extra for access. If not, try contacting the author–most authors are happy to send you a copy of their scholarly article for free.

Remember to follow the advice in the section on Evaluating Sources to determine whether information you locate online is suitable for your information needs.

How to Use Them

Use of each tool varies; see the links above for examples. If a search engine has an advanced search, it may include options such as specifying format, language, domain, or date range. Many web search tools have a page or knowledge base that explains how the tool works and provides search tips for different use cases. Look for a link to this information at the top or bottom of the page or next to the search bar. For example, here’s Google’s page about how their search engine works ⧉. If the documentation is unclear, feel free to consult a librarian for help–they can help with web searches, too, not just searching library resources.