Searches
Advanced Searching
Using Boolean Operators and Other Modifiers in Searches
Simply typing a word or two into a search box and
clicking on the search button is fine for quick,
rudimentary searches. Many times, however, doing only that will result in thousands of hits, which may
themselves require a lot of searching and sorting to find
the ones that are useful to you. Wise use of modifiers
can help you to fine-tune your search so that you will
come up with better results that take less reviewing on
your part.
Often, using advanced search techniques will save time
overall. Although you will use a few minutes more to set
up a search, that effort will be offset by the more
useful results that you will obtain.
Search modifiers take two forms – words and
symbols. Here is a brief list of many of them with a
description of how each one should be used.
Be aware that search engines vary in what operators
and modifiers they accept and in how they use them. The
material below is a generalization. Some of the words and
symbols listed may not function on some search engines.
To obtain best results with any particular search
engine, read the documentation provided at its site (usually
available through a Help link) and try different
operators and modifiers to learn how they work. Also be
aware that some search engines use variations of the
standard forms of operators. Some of those variations are included
below.
Examples listed below are in all caps. Some search
engines may accept Boolean operators when they are not in all caps,
but it is usually safer to use the all-caps form.
Boolean Operators (Words)
AND – Use AND to limit a search.
In the example here, searching for the two words
"rock" and "music" with no operator would
deliver hits represented by the two larger rectangles (pages
in which either of the two words appeared). Inserting the
Boolean operator "AND" would restrict results
to only those pages on which both words appeared.
Use of AND will return pages on which both of
the words appear, regardless of where they are on those
pages. For example: "Blongo is an island composed
mostly of rock, but the wind makes beautiful music
in the trees.
rock AND music
NEAR – Use NEAR to restrict a search more narrowly than AND.
Putting NEAR in a search string tells the search
engine to return only those pages on which the terms
linked by NEAR appear within a certain number of words of
each other. Depending on the search engine that you are
using, you may be able to designate that number or you
may have to use the engine's default number of words.
(Variation: NEAR/#, where # is replaced by the amount
of separation you will accept. "NEAR/5" would
mean that the two terms must be within 5 words of each
other.)
Christmas NEAR tree would (if the
default were 10 words) return pages that contain
expressions such as "Christmas customs include
decorating a tree, exchanging presents …"
NOT – Use NOT to limit a search.
Suppose you want to find information about apple (the fruit -- not the computer manufacturing company). Constructing a search using "not" would eliminate the latter from potential hits.
apple NOT computer
(Variations: AND NOT; BUT NOT)
OR – Use OR to expand a search.
Different sites sometimes use different terms to refer
to things. Some might use the word "cars" for
the vehicles that many people drive. Others might use
"automobiles." Thus, if you were doing research
about those vehicles, you might want to broaden your search by using both terms connected by OR.
Use of OR will return pages on which either
of the words appears.
Using OR can also be helpful if you are not sure how
to spell a word (or if you are not sure whether Web page
designers spelled it correctly). You can combine several
variations with OR to increase your chances of finding
something you need.
cars OR automobiles
Note: When you enter more than one term with no Boolean operator, each search engine applies its own default operator. For almost all major search engines, the default is AND. If you are not sure about a particular search engine's default, check the documentation on its site.
Symbols Used as Modifiers
Searches can involve symbols in place of – or in addition to – words as operators. A list of search symbols and their meanings follows. These symbols are used widely, but they may not apply to all search engines. Consult the documentation at each search site to determine what symbols it accepts and how they are interpreted. The table below presents a general overview that applies to many search engines.
| ( ) | Parentheses are used for grouping to establish precedence of operations when several operations appear in one expression. For example, newspaper AND (editor OR designer) would first find all pages containing "editor," "designer" or both and then keep only those pages containing "newspaper." |
| ! | The exclamation point before a term means the same as NOT. |
| & | The ampersand means the same as AND. |
| | | The piping symbol (usually found as the shifted version of the backslash key) means the same as OR. |
| ~ | The tilde means the same as NEAR with some search engines. With Google, however, putting a tilde before a word instructs the search engine to look for the specified term and its synonyms. |
| " " | Double quotation marks around an expression indicate that the search engine should return only pages containing that exact expression. "Lady Techsters" in a search would tell the search engine not to return a page about Lady Astor or one that said, "Victory came to the Techsters," unless, of course, "Lady Techsters" also appeared on the same page. |
| + | A plus sign immediately before a word (with no space between the sign and the word) means that the word must appear in all pages returned. |
| - | A minus sign immediately before a word (with no space between the sign and the word) means that the word should not appear in any page returned. |
Capitalization
Capitalizing the first letter of a word indicates that you want only pages on which the word appears that way. It is more limiting than putting the word in all lower case. Entering "Newt" in a search box would return pages mentioning former Speaker of the House Newt Gingrich but not pages about a salamander. Using "newt" instead would return pages about both.
Note: A good presentation about using Boolean operators is found on the University of Albany's University Libraries' Web site at http://www.internettutorials.net/boolean.html.