Keywords allow you to construct a search that reflects multiple issues in your research question. Building sets of related concepts and looking for their overlaps gives you more relevant and precise results. This approach is called Boolean searching using the operators (AND, OR, NOT).
For example, a search for old age AND health care will return items that contain both of the concepts:
older OR elderly returns items that contain either one of the terms or both:
medicare NOT medicaid returns items that discuss the health program for the elderly but do not mention Medicaid:
Enclose phrases in quotations marks. This is an important strategy for getting exact results when searching phrases (e.g., "american anthropological association") or conducting known-item searches for titles.
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, politicians, and so on.
Wildcard searches are for differences within words: a search for wom?n will return results for woman, women, and womyn.
When pairing two or more keywords with another keyword, it is important to "nest" the former terms within a larger Boolean search.
For example, (older OR elderly OR aged OR aging) AND (politic* OR economic*) will return results for the union of the two subject areas.