"Search engines are programs that search documents for specified keywords and returns a list of the documents where the keywords were found. A search engine is really a general class of programs, however, the term is often used to specifically describe systems like Google, Bing and Yahoo! Search that enable users to search for documents on the World Wide Web."
~ from Webopedia
Practically all the major search engines support phrase searching. Phrase searching is where a search engine will find documents that contain words in the exact order you specify. You do this by enclosing your terms with "quotation marks". For example a search on "distance learning courses" would retrieve only pages that have all those words in that exact order and would not retrieve a site that said "learning at a distance".
Be careful using this type of search. You may be narrowing your search too much or using a combination of words that is not found in the indexed pages. This could render zero results even though there may be something relevant on the pages.
How to understand and use these clever logic tools to improve your search results.
emilyatchemlib. (2008, April 24). Boolean operators [Video file]. Retrieved from http://www.youtube.com/watch?v=xsSZps3NH-M
OR = Match Any Search
The Boolean OR command is used in order to allow any of the specified search terms to be present on the web pages listed in results. It can also be described as a Match Any search. Sometimes you want pages that contain any of your search terms. For example, you may want to find pages that contain either of the words rules or laws.
You use the command like this: rules OR laws
Using OR to link your terms will broaden your search and increase the number of results. Note that OR works only in upper case between search terms in Ask.com, Google, Live Search, and Yahoo!
AND = Match All Search
The Boolean AND command is used in order to require that all search terms be present on the web pages listed in results. It can also be described as a Match All search. For example, you may want to find pages referencing both rules and laws.
You use the command like this: rules AND laws
Since AND is the default operator in search engines, it is unnecessary to type it. For example, you can type rules laws and your results will retrieve pages that include both rules and laws on the same page.
NOT = Exclude Search
The Boolean NOT command is used in order to require that a particular search term NOT be present on web pages listed in results. It can also be described as an Exclude search.
You use the command like this: plants NOT trees
Using NOT will work in Live Search and Yahoo! However, when using Ask.com and Google, you must use the "-" sign without spaces.
You use the command like this: plants-trees
* = Wildcards
You can search for plurals or variations of words using a wildcard character. It is also a great way to search if you don't know the spelling of a word. The * symbol is used as the wildcard symbol.
The format looks like this:
- learn* - finds learning and learners
- hous* - finds houses and housing
Google supports full-word wild cards such as star * banner, and is supported in databases such as LexisNexis, but will not work in Yahoo! Ask.com, or Live Search. Single letter wild cards, such was wom*n do not work in most major search engines. We recommend that you become familiar and comfortable using 2-3 search engines. Remember to review the special features that each search engine offers to get the most out of your online time.
Boolean commands, developed by Mathematician George Boole in the mid-18th century, express the relationship of two or more concepts. The most commonly used operators — AND, OR, and NOT — can be used to link search terms or narrow search results.
Boolean logic is a system of rules, formulated in 1847 by the mathematician George Boole, that represents relationships between entities—either ideas or objects. Those very rules, or Boolean operators, can help with your research! Whether you conduct your search across an internet search engine, a library catalog or research database ‐ the correct use of Boolean operators within your search criteria will produce better results.
w/x = Proximity Search
Proximity searches are used in order to specify how close terms should appear to each other. They are not supported in major search engines such as Ask.com, Live Search, Google, or Yahoo! But can be used in some databases, such as LexisNexis.
You use the command like this: baseball w/2 stadium
( ) = Nesting
Nesting allows you to build complex queries. You nest queries using parentheses, like this: impeachment AND (Clinton OR Nixon)
Major search engines such as Google, Ask.com and Yahoo! do not support nesting. However, Live Search supports nesting as do some databases such as LexisNexis.