Searching the Web
Lesson 3: Using Search Engines and Metasearch Engines
Using Boolean Logic Operators
If the words “Boolean Logic” bring back nightmares from high school math class, fear not! Boolean logic operators are easy to master (not to mention massively useful) when searching on the Internet. Boolean operators serve to narrow or broaden your searches by allowing you to get very specific about what you want to see in your search results. There are three Boolean operators that you should become familiar with: AND, OR, and NOT.
AND
The AND operator narrows a search by requiring all terms linked by this operator to be included in the search results. For example, doing a search on “peanut butter” AND jelly will require that BOTH terms be included on all pages in the search results. This would give you a lower number of search results because AND narrows your search.
OR
The OR operator broadens a search by allowing any of the terms linked by this operator to be included in the search results. For example, doing a search on “peanut butter” OR jelly will require that EITHER term be included on all pages in the search results. This would give you a higher number of search results because OR broadens your search.
NOT
The AND operator limits a search by prohibiting the terms linked by this operator to be included in the search results. (Some tools use AND NOT or BUT NOT instead of NOT.) For example, doing a search on “peanut butter” NOT jelly will require that “peanut butter” appear on the search results pages, but only those pages that do not mention jelly. This would give you a lower number of search results because NOT limits your search.
IMPORTANT NOTE:
- Not all search tools permit the use of the Boolean Logic operators, so read the help files or FAQ.
- Some tools require that you type the Boolean operators in ALL CAPS, while others may have other restrictions or options (such as pull-down menus or check boxes). Be sure to read the help files or FAQ.
Check it out!
- See Figure 4.3 on page 67 of The Extreme Searcher’s Internet Handbook for a graphic example (Venn diagram) of Boolean Operators.
- Want to know who Boolean Logic was named after? See the Boolean glossary entry on page 224 of The Extreme Searcher’s Internet Handbook.
Boolean Combos and Parenthesis
You can use the Boolean operators in combination with one another (as well as phrase searching techniques) to build very specific searches. Adding parenthesis to the query can make for some very complex and precise searches. Some examples follow:
If you were searching for searching for ragtime sheet music by composer Scott Joplin, you could build the following search:
Ragtime AND “sheet music” AND “scott joplin”
If you were searching for searching for ragtime sheet music but didn’t want any from composer Scott Joplin, you could build the following search:
Ragtime AND “sheet music” NOT “scott joplin”
If you were searching for searching for ragtime sheet music by composer Scott Joplin or Joseph Lamb, you could build the following search:
Ragtime AND “sheet music” AND (“scott joplin” OR “joseph lamb”)
If you were searching for searching for ragtime history or sheet music by composer Scott Joplin, you could build the following search:
Ragtime AND (“sheet music” OR history) AND “scott joplin”
The parenthesis serve to separate out a statement, and make your query more precise.
IMPORTANT NOTE:
Not all search tools permit the use of the parenthesis in searches, so read the help files or FAQ. (You knew that was coming, didn't you?)
Try this!
Visit the AllTheWeb search engine (http://www.alltheweb.com/) and try the searches below. Use Boolean Logic operators (AND, OR, NOT), as well as phrase searching techniques (quotation marks). Search for:
- Apple pie recipes that include brown sugar or lemon
- Apple pie recipes that don’t include brown sugar but do include lemon
- Reviews of color printers that are compatible with Macintosh computers
- Reviews of color printers that are not compatible with Macintosh computers
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