 In this video, we'll cover subject terms and controlled vocabularies and how they can help you with your searching. Much of the searching we do is keyword searching. The database looks for the words we've entered in our searches and returns items that have the words in their records, perhaps in their titles or in the case of journal articles in their abstracts. Keyword searching is often effective, but it has a significant drawback. We have to use the same words that the authors of relevant sources used in order to find them. There are many ways to refer to many concepts. For example, if one of the core concepts in a research topic were teenagers and we searched that term within our search strategy, we may retrieve some relevant results, but we may miss a lot because scholars might be using other terms like adolescence or youth. In other videos, we talked about addressing this problem by listing synonymous and like terms and incorporating them into our search using the Boolean operator OR. We also talked about casting a wider net with your search using techniques such as truncation. But in many databases, there is another way around this problem, subject terms. Subject terms, also called subject headings, are words that describe the topic of an item, recognizing that searchers need effective and efficient ways of finding sources on defined topics. People have developed what are called controlled vocabularies, which are long lists of subject terms. Each subject term corresponds to a concept, and each concept should have no more than one subject term. Using our earlier example, the concept teenagers should have a single subject term in a given database. Let's say that in the database we're using, the subject term is adolescence. If we run a search for the subject term adolescence, we should retrieve everything in the database about that concept, whether the authors use the word adolescence or another word like teenagers, teens, or youth. This can be a great time saver. But how do you know what the subject terms are? How would you know, for example, that it's adolescence and not teenagers? This will depend on the database you're using and your own approach to searching. You might start with a keyword search and look through your results to identify relevant subject terms. Subject terms should be listed in the record for each item in the database. When you find a potentially helpful subject term, go back to the search boxes and copy it into the appropriate line, specifying that it's a subject term, using the field selection drop down menu. Alternatively, you can search the controlled vocabulary directly. Depending on the database you're using, you might do this through a checkbox located above or below the search box or boxes. Or there may be a thesaurus or subject terms tab you can select to run a search of the controlled vocabulary. In the library catalog, you select subject heading and the drop down menu before running your search. Be sure to ask us if you're having trouble searching a controlled vocabulary. Subject terms can make a big difference in searching, but there are a few things to keep in mind. First, not all search tools have a controlled vocabulary. Google Scholar and the library SummonSearch don't have controlled vocabularies, and so you must run keyword searches when using these tools. Second, different databases use different controlled vocabularies, so just because a word was a subject term in one database doesn't mean it will be a subject term in another. And third, you might occasionally be working with a core concept that doesn't have an appropriate subject term in the database you're using. In this case, you might instead have to use keyword searching for that particular concept. It can be challenging to understand how subject terms work and how to use them effectively, so please don't hesitate to reach out to your subject librarian or our research help service if you have any questions.