Boolean operators are named for George Boole (1815-1864), an English Mathematician and Philosopher. Boolean Algebra and Symbolic Logic both derive from his work. Boole is generally considered the father of modern computer science. Most electronic indexes (databases) require the use of Boolean operators in parsing search terms, although this is not always apparent. Boolean search statements are incredibly powerful in retrieving what you need provided 1) the statement is formatted correctly and 2) your choice of search terms is correct for the topic you are researching.
Rather than typing a full sentence or question into a search box, using Boolean operators can help you create an efficient and effective database search.
Try the Search Strategy Builder, which will create searches out of keywords that you supply!
Example Boolean search statements using boolean operators, symbols, and/or advanced techniques:
(single-molecule fluorescence OR SM fluorescence) AND molecular biology
("single-molecule fluorescence" OR "SM fluorescence") AND cellular activit*
(Calcium AND milk) NOT goat
child* AND anxiety AND (exercise OR "physical activity")
alcohol AND medication AND (elderly OR aged OR older adults)
alcohol AND "drug interactions" AND (elderly OR aged OR older adults)
alcohol AND ("medication interactions" OR "drug interactions") AND (elderly OR aged OR older adults)
Read more about Boolean searching here: http://www.nlm.nih.gov/bsd/disted/pubmedtutorial/020_350.html
Truncation: A symbol, specific to the search interface, which allows the retrieval of all endings for the specified base word. An asterisk (*) isoften used. For example, child* would retrieve records with children, childish, and every other word that begins with the root word "child."
Wildcard: A symbol, specific to the search interface, which allows the retrieval of various spellings of a word. A questio mark is often used. For example, wom?n would retrieve records with women or woman.
Quotation marks: To search for an exact phrase with the words together, in the order you wish to find them, add " " quotation marks around the phrase, such as "physical activity" versus finding an article about physical education and an activity for elementary school students.
Read more about these sorts of tricks here: http://addison.vt.edu/screens/help_index.html#tips