Most catalogs and databases search for your terms as keywords anywhere in their records, including title, author, table of contents, summary, subject, and full text.
This often leads to an overwhelming level of irrelevant results. Advanced search and subject searching helps narrow your results.
Most databases have advanced search options that allow you to narrow your search to only those parts of the record you want to search and to combine search terms.
For example, in the screencap below the Advanced Search dropdown menus have been set to return only results that discuss both local law AND climate change in the abstract. This excludes results that discuss only local law or only climate change or that mention these topics only in passing.
Most databases have subject terms that allow you to pull a list of all articles or books on a specific subject. Usually, a link to the database's subject terms is located near the top of the screen and labeled "Thesaurus" or "Index".
For example, in the screencap below, the user has accessed the "Thesaurus" link at the top of the screen, searched for the term "zoning," and then automatically created a search that will retrieve all articles on zoning and related topics.
Most databases suggest related terms you might also try and offer "Explode" checkboxs that automatically search for both your term and all related terms.
All library catalogs categorize books by subject. Usually, the easiest way to find relevant subject terms is to run a keyword search. Once you have found a relevant book, look at the end of the book's page for a section labeled "Subject" and then click on the listed subject to retrieve all books and ebooks on that subject.