What Is a Boolean Search?

A Boolean search is a method of using a search engine that allows you to combine words and phrases using the words and, or, not, and near, along with the + (add) and - (subtract) symbols to limit search results and reduce the number of unrelated results that are returned.

These words and symbols are known as Boolean operators, and you can use them to limit, widen, or define your search. Most internet search engines and web directories default to these Boolean search parameters anyway, but knowing how to use these operators can make your searches more efficient, convenient, and successful.

George Boole, an English mathematician from the 19th century, developed an algebraic method that he first described in his 1847 book, The Mathematical Analysis of Logic and expounded upon in his An Investigation of the Laws of Thought (1854). Boolean algebra is fundamental to modern computing, and all major programming languages include it. It also figures heavily in statistical methods and set theory.

Today's database searches are largely based on Boolean logic, which allows us to specify parameters in detail — for example, combining terms to include while excluding others. Given that the internet is akin to a vast collection of information databases, Boolean concepts apply here as well.

Using Boolean logic to broaden or narrow your search is not as complicated as it sounds; in fact, you might already be doing it. A Boolean search simply entails certain logical operations to combine search terms.

To use Boolean concepts in a search, you have two choices: You can use the standard Boolean operators or their math equivalents. It depends on your preferences and what you're most comfortable with.

For the purposes of an internet search, here are the terms and symbols you need to know:

• The Boolean search operator and is equal to the + (plus) symbol.
• The Boolean search operator not is equal to the - (minus) symbol.
• The Boolean search operator or is the default setting of any search engine — meaning, all search engines will return matches for any of the words you enter.
• The Boolean search operator near is equal to putting a search query in quotes, e.g., "sponge bob squarepants." You're essentially telling the search engine that you want all of these words, in this specific order or this specific phrase.

Believe it or not, basic math can help you with web searches. Here's how:

• The minus symbol: Use the - symbol when you want a search engine to exclude the term immediately following it. For example, if you search for Superman -Krypton, you are telling the search engines to find pages that include "Superman," but not "Krypton." Using the minus symbol to mean "not" is a simple way to eliminate extra information and narrow your search.
• The plus symbol: Now that you know how to eliminate search terms, here's how you can add them using the + symbol. To specify terms that must be returned in all your search results, place the plus symbol in front of the relevant term. For example, football +nfl will produce results that include both these words. Conversely, entering football nfl in the search box will return pages that include one word or the other, or both. Remember, the plus symbol means "and."
• You can combine operators, too, for more complicated, targeted searches. For example, you could enter superman -krypton -"lex luthor" to find pages that include "superman" but neither "krypton" nor the entire phrase "lex luthor."