Keyword vs. Subject

Doing a "Subject" search searches only assigned subject headings. A "Keyword" search will search titles, subjects, abstracts, etc., and so is a broader, though less focused, search (i.e., it will likely retrieve more results, but will also likely include some less relevant results and miss some useful information).

Keyword: find any record with "shakespeare" in the title or contents, or as an author or subject.	Subject: find only those records with "shakespeare" as a subject.

Concepts can often be described in different ways and with different terms. Many indexes and databases use a standardized list of subject terms to describe topics (called a controlled vocabulary). This is very helpful if you know the standardized subject heading, because you can do one search to find everything in the database on a particular topic rather than having to do several searches.

For example, if you know a database uses the term "aged" as a standardized subject heading, you can do one search for the subject "aged" and know that you have also retrieved articles on "senior citizens" and "elderly." Some databases will offer a thesaurus to direct you to their chosen subject headings.

If you do not know the appropriate standardized subject terms for your topic, do a keyword search first. With a keyword search, you use your own words or phrases to describe your topic; the computer will find all the citations in the database that have those words anywhere in their titles, subject headings, abstracts, or full text. Keyword searches often turn up too much information, and sometimes much of it will be unrelated to your topic. When you find a few appropriate citations, use their subject headings to do a more focused subject search to locate all items with the same subject headings.

For example, if you search in an online library catalog that uses the Library of Congress subject headings and look for books on "cultural evolution," a keyword search would retrieve this record for the book Cultural Evolution: Contemporary Viewpoints. But note that "cultural evolution" is not listed in the subject headings. A subject search would not have found this book. But a subject search for "social evolution" will find all books with titles about "cultural evolution," "cultural change," "social development," and other synonyms.

Note, however, that some databases (typically, those which do not use a list of standardized subject headings) use the term "subject" search when they really mean a "keyword" search. Knowing the type of search you are actually doing can help you understand why you got your search results and how to use those results (e.g. if there is no real subject search, you may have to use other search techniques to make sure you have found all the relevant information available in the database).