1.4. Logical operators
One of the most basic and yet productive techniques when searching for information on the Internet is the use of logical operators between keywords. This type of search is called a Boolean search, after the English mathematician George Boole, who created a logical system to relate or exclude concepts. Most search engines understand and accept logical operators (AND NOT, NEAR and OR) and their equivalences as mathematical symbols.
| Logical operator | Mathematical symbol | Description |
|---|---|---|
| AND | + | It tells the search engine to show results that contain both of the words linked by the operator. For instance, Sitges AND modernism will retrieve pages that contain both concepts. |
| NOT | – | It tells the search engine that we want to find the word before the operator, but excluding the word after the operator. For instance, Sitges NOT modernism will provide pages about Sitges that include no references to modernism. |
| OR | White space | At least one of the words should appear on the page. In this case, Sitges OR modernism will show us pages that refer to either Sitges or modernism (nevertheless, by default, it will show first those pages that contain both terms). |
| NEAR | Put the word in quotation marks | This is the way to ask the search engine to show results that contain both words in a row. In this case, Sitges NEAR modernism will retrieve pages where a word is next to the other or close by. |
Even though the asterisk (*) may not be considered an operator, search engines consider it a wild card. Thus, moder* will provide results that contain words such as modernism, modern, moderation, etc.
The operators mentioned above (or their equivalents) may be used in combination, which means that the search may be further refined. For instance, the expression “Sitges moder*” NOT painting will retrieve pages that contain Sitges and modernism (or modernity or modern, etc.) and do not include the concept “painting”.