Boolean Logic

George Boole, English mathematician, developed Boolean Logic, also known as the "mathematics of logic", in the mid-19th century. Boolean Logic is the foundation of all electronic circuits in a computer and is used whenever searching on the Internet. It primarily consists of 3 functions:
  1. AND divides search words or phrases and is used to narrow a search (In most search engines, the + sign can be used in place of the word AND in all caps). For example: dog AND poodle will return "hits" for Web sites that contain both dog and poodle.
  2. OR combines search words or phrases to widen a search. For example: dog OR poodle will return "hits" for Web sites that contain either dog or poodle.
  3. NOT eliminates like words or phrases to narrow a search. For example: dog NOT poodle will return "hits" for Web sites that contain dog but not poodles. (In most search engines, the - sign can be used in place of the word NOT in all caps).
Most search engines allow you to use shortcuts, or implied Boolean operators, like the plus (+) sign for AND or the minus (-) sign for NOT. Some search engines require you to use their Advanced Search features to take full advantage of Boolean Logic.

Below are some links to resources about Boolean Logic. Please add additional resources on Boolean Logic in alphabetical order below: