In order to limit overly broad searches (that result in too many results), or to expand ovelry narrow searches (that result in too few results), use Boolean operators (AND, OR, NOT), which allow one to limit or expand searches depending on his or her needs.
For example, a search for Resnais AND Holocaust will return items that contain both "Resnais" and "Holocaust":
Resnais OR Holocaust returns items that contain either "Resnais" or "Holocaust" or both:
Resnais NOT Holocaust returns items that contain "Resnais" but not "Holocaust":
Phrase searching:
An important strategy for one to employ when researching phrasal concepts (e.g., "European Union") or conducting known-item searches for titles:
For example, Hiroshima Mon Amour will search for Hiroshima AND Mon AND Amour.
However, "Hiroshima Mon Amour" in quotation marks will search for Resnais' film of the same name.
Nested Searching:
When pairing two or more keywords with another keyword, it is helpful to "nest" the former terms within a larger Boolean search.For example, (memory OR nostalgia) AND Resnais will return results for Resnais and any one (or both) of the parenthetical terms.
(Many catalogs or databases will have an "advanced search" option, which provides multiple search bars to facilitate nested searching.)
Truncation and Wildcards:
Most catalogs and databases enable users to search variations of keywords by using truncation (*) or wildcard (e.g., ?, $, !) symbols.
For example, one could search for politic* to find poltic, politics, political, politicking, and so on.
Wildcard searching works similarly: a search for t??th will return results for teeth, tooth, tenth, and so on.