Why keywords can miss relevant sources
Imagine you are looking for research on gardens maintained by people in cities. You might search for “city gardens,” while a useful book uses “urban gardening” and an article uses “community gardens.” A keyword search depends partly on whether your chosen words appear in the fields the catalog or database searches. Changing a word can change the results, even when your underlying question stays the same.
Subject headings offer another route. They are descriptive labels assigned to records according to a catalog or database’s system. Rather than relying only on the words an author chose for a title or abstract, you can search or browse records grouped under a shared topic. The exact heading and the way it is applied depend on the resource you are using.
What a subject heading does
A subject heading is a standardized term used to describe what a source is about. A catalog might use one preferred heading for a topic even though readers search for it in several ways. Some systems also connect that heading to related, broader, or narrower headings. These connections can help you move from an initial idea to a more precise part of it, or widen your search when you have found too little.
The important distinction is between words in a record and labels assigned to the record. A title might mention a garden only as an example, while a subject heading generally signals that the topic is a substantial focus of the source. That signal is useful, but it is not a guarantee of relevance. You still need to inspect the title, summary, and, when possible, the source itself.
Find headings from a promising result
Start with a simple keyword search in a library catalog or research database. Open a result that seems close to your question, then look in its detailed record for fields labeled “Subjects,” “Subject terms,” “Descriptors,” or something similar. Note any heading that describes the part of the topic you care about. If the interface makes the heading clickable, follow it to see other records carrying that label.
Suppose your question concerns how neighborhood gardens affect access to food. A promising record might show separate headings for community gardens and food access, though the actual wording will vary by database. Searching the garden heading alone could reveal sources with unfamiliar terminology. Combining it with a food-related heading could narrow the set toward your question. If a heading leads mostly to unrelated material, return to the record and try another one.
Combine headings with your own language
Subject headings work best as one part of a search, not as a replacement for keywords. First, list a few ways an author might describe your topic. Then collect relevant subject headings from useful records. Search those headings in the database’s subject field if that option is available, and run separate keyword searches for terms that may not appear in the heading list. Keep track of which combinations produce sources worth reading.
You can also use headings to adjust scope deliberately. If a heading is too broad, look for a narrower heading or combine it with another concept, such as a population, place, or outcome. If it is too narrow, try a broader heading and screen the results yourself. Before using AND or OR between terms, check the database’s search help: interfaces differ in how they handle subject fields, phrase searches, and combinations.
Know when to look beyond the heading
No subject-heading system captures every useful source. Different databases may use different labels, and some records have sparse or inconsistent subject information. A new source may also be searchable by its title before it has detailed subject terms. Topics that cross disciplines can be particularly difficult to represent with a single heading, so searching more than one catalog or database may expose different ways of organizing the subject.
Use headings as clues to how a collection is organized, not as a final judgment about what matters. When you find a strong source, examine its subject terms, but also read its abstract or introduction and follow relevant references. Move back and forth between the language you use, the language authors use, and the labels databases assign. That process is often more productive than trying to guess the one perfect keyword at the start.
