Start with the words your sources might use
Finding sources is often less about guessing one perfect phrase and more about trying several ways to describe an idea. Suppose you are looking for studies on how public libraries help adults learn digital skills. A search for libraries digital skills may give you a useful starting point, but it could also retrieve sources about school libraries, library staff training, or children’s programs. Boolean operators let you describe which ideas must appear together, which words can stand in for one another, and which meanings you want to leave out.
The three basic operators are AND, OR, and NOT. Many academic databases and library catalogs recognize them when written in capital letters, although the exact rules vary by search tool. Before building a long query, try a few ordinary keywords and inspect the results. Notice the language authors use in titles and summaries. Those terms will help you build a search that reflects the sources you want to find, not just the words you first thought of.
Use AND to connect different ideas
AND asks a search tool to find results containing both terms or groups of terms. For example, libraries AND digital skills is intended to find material mentioning both concepts. Add a third distinct idea, such as adults, and the search may become more focused: libraries AND digital skills AND adults. This can help when a broad search produces too many results.
Every added requirement can also hide a useful source. A relevant article might discuss “digital literacy” rather than “digital skills,” or use “public library” only in its summary rather than its title. If your results become sparse, remove an AND term and see what returns. Think of AND as a way to express the essential parts of your question, not as a reason to include every related word you can imagine.
Use OR to capture alternative terms
OR connects words or phrases that could describe the same part of your topic. A source about digital skills might instead use “digital literacy” or “computer skills.” Searching for “digital skills” OR “digital literacy” OR “computer skills” gives each phrase a chance to match. Quotation marks commonly tell a search tool to treat the words inside them as a phrase, but check how the tool you are using handles quotes.
Parentheses make a search with several ideas easier to read: libraries AND (“digital skills” OR “digital literacy”) AND adults. Here, the words inside the parentheses offer alternatives for one concept, while AND joins that concept to the others. OR usually broadens a search, so include alternatives that are genuinely relevant. Adding a loosely related word may bring in many results that do not answer your question.
Use NOT carefully to exclude an unwanted meaning
NOT tells a search tool to leave out results containing a specified term. If a search about adult learning keeps returning material focused on children, you might try libraries AND “digital literacy” NOT children. This may reduce that particular kind of result. In some tools, a minus sign performs a similar exclusion, while others have their own search rules.
Exclusion has a cost: a valuable source about adult programs might mention children in a comparison and disappear from your results. Before using NOT, look at a sample of the results you want to avoid and identify the term that actually distinguishes them. Then compare searches with and without the exclusion. If you are reviewing sources for a substantial project, favor a broader search and screen the results yourself rather than relying on NOT to make every relevance decision.
Build, test, and revise your search
A practical sequence is to name two or three main concepts, list alternative terms for each, and combine them one step at a time. For the library example, you might begin with libraries AND “digital literacy.” If the results seem too narrow, try (libraries OR “public libraries”) AND (“digital literacy” OR “digital skills”). If they are still too broad, add adults as another required concept. Scan titles and summaries after each change to see whether the new results are closer to your question.
Search tools do not all interpret Boolean operators, parentheses, quotation marks, and word endings in the same way. Some also offer field searches or filters for source type, subject, or publication period. When a query behaves unexpectedly, check that tool’s search help and simplify the query before adding more syntax. Keep a brief record of the searches that worked, especially for a longer project. The goal is not to construct the most complicated search string; it is to find a range of useful sources you can evaluate.
