Leslie Ann Bowman

Coordinator of Instructional Services, Joseph W. England Library

Associate Professor, Information Science

Search Tools

Every search system has its own tools to assist the searcher. To find the tools available for a particular system, look for a ‘Help’ or ‘Search Tips’ button on its main search page. Some of the most common search tools used in constructing searches are:

AND, OR, and NOT: These are known as the Boolean operators. They are used to combine terms to produce the desired search results. Most indexes and catalogs allow searchers to use the Boolean operators, as do many Internet search engines.

AND produces the intersection between two sets. For example, a search for ‘lions AND tigers’ will result in items that discuss BOTH lions AND tigers; the set will not include items that discuss only lions. AND is usually used to combine two different concepts such as 'cancer' AND 'treatment'.

OR produces the union between two sets. For example, a search for ‘lions OR tigers’ will result in items that discuss EITHER lions OR tigers; the set will include all items that discuss lions and all items that discuss tigers. OR is usually used to combine synonyms or similar concepts. For example, a search strategy for items about cancer might include the following: cancer OR carcinoma OR tumors OR neoplasms.

NOT subtracts the contents of one set from that of another set. For example, ‘lions NOT tigers’ will result in items that discuss ONLY lions without mentioning tigers. NOT is seldom used and when it is used, the searcher must be very careful not to accidentally eliminate wanted items.

Parentheses ( ): Complex search strategies that combine more than one of the Boolean operators can be difficult to read and understand for both the searcher and the search system. The use of parentheses helps to make clear the searcher’s intentions. Most search systems will search those sets within parentheses before other sets. Sets being combined with OR should always be put in parentheses if AND is also being used in the same search. For example: for a search on the treatment of cancer, consider the following strategy:

treatment AND cancer OR carcinoma OR tumors OR neoplasms

At the start of the search, items on both treatment and cancer will be found, then to that set ALL items about carcinoma, ALL items about tumors and ALL items about neoplasms will be added. The search results will include articles about carcinoma, tumors and neoplasms that do not discuss treatment.

Now consider the same search with the addition of parentheses:

treatment AND (cancer OR carcinoma OR tumors OR neoplasms)

In this search, the parentheses indicate that the first step of the search is to combine the four cancer terms into one set, then that large set will be combined with ‘treatment’ to find only those items that are about both treatment and cancer.

+ and -: These symbols are most commonly used by Internet search engines, but they sometimes are used by other search systems as well. They are used in place of AND and NOT. Most Internet search engines combine terms using OR unless otherwise instructed.

+ requires that the following word be included in the results set. For example, the search ‘+lions +tigers’ will result in items that discuss BOTH lions AND tigers. It has the same result as the search ‘lions AND tigers’.

- requires that the following word be excluded from the results set. For example, the search ‘lions –tigers’ will result in items that discuss ONLY lions without mentioning tigers. It has the same result as the search ‘lions NOT tigers’.

Quotation marks (“ ”): Quotation marks are often used around two or more words when the searcher wants the words to be found in an exact match. An exact match has the same words in the same order with no other words included in the phrase. For example, the search “lions and tigers” will result in only items that include the phrase “lions and tigers” but will not include the phrases “tigers and lions” or “lions and white tigers”.

Truncation (also known as Stemming or Wildcards): Truncation allows a searcher to search for multiple forms of a word that share the same stem. This allows a searcher to retrieve both singular and plural forms of a word along with other related words. Truncation is usually indicated by a special symbol such as ‘?’, ‘$’ or ‘*’ at the end of a word. Truncation may result in the retrieval of some items that are not relevant to the searcher’s needs. For example, a search for ‘lion?’ will result in items that include any of the following terms: lion, lions, lioness, lionesses, lionfish and lionfishes. A searcher looking for information on the large African carnivores will be pleased to retrieve the first four terms but may not be at all interested in ‘lionfish’ or lionfishes’. Search systems may have restrictions on how many different words may be retrieved using truncation. Some search services automatically truncate all terms in all searches. A search service’s Help or Search Tips page usually includes instructions on whether the searcher must use a special symbol for truncation and, if so, which symbol to use.