Systematic Reviews

Subject terms or controlled vocabulary, are specific words or phrases that were assigned by a database to describe the article, book, or record. Library databases use searchable thesauri to arrange these subject terms.

• You can think of these as the "hash tags" used by a database to organize it's content, and make it easy to find all results about a specific subject. It is possible to search for articles using subject terms from database thesauri, rather than using keywords. 
• Since subject terms reflect the main focus of the record, searching by subject can be a rapid way to narrow results to a particular topic. 

A systematic search will use a combination of both keywords and subject terms/controlled vocabulary for a comprehensive literature search.