A subject heading is a standardized word/phrase which has been assigned to a certain topic by a recognized authority. Think of them as "key concepts" (see Lesson 2) that are universally applied and used to group various resources together.
"Standardized": This means that the list of subject headings is determined ahead of time and never changes. The subject heading "Peanuts" will always be "Peanuts" and never anything else. Furthermore, for every broad subject heading like "Peanuts," there are usually several "sub-topic" subject headings as well, such as "Peanuts--Harvesting," "Peanuts--Prices," or "Peanuts--Standards."
"Recognized authority": This means that for every resource that has been given a subject heading, a librarian (probably from the Library of Congress--LOC) has taken the time to look thoroughly at that resource, determine what it is about, and select the subject headings that apply to it. Subject headings are not tagged onto resources by just anybody. They are assigned by professionals whose job is to classify materials so that they are easier to find.
In the 1800s, the LOC created a set of standardized "tags" that all their catalogers were required to use to ensure that all the material on one topic could be found in one place. These tags are a controlled vocabulary, created and moderated as an effective alternative to "folksonomies" (user-created tagging systems that are not centrally controlled, like hashtags). Because these standardized tags exist, we do not have a system in which one library catalogs a book with the subject "New York," while another catalogs the same book under "New York City," and yet another catalogs it under "NYC." Instead, everybody catalogs it under the same subject headings.
Searching by subject headings can be much more effective than searching by keywords. Not only are subject headings universally recognized, they are also consistent across all cataloged media (books, journals, videos, music, etc.) and virtually every scholarly database and catalog in the country.
Here is an example of how searching by subject headings can be so effective:
Suppose you are researching euthanasia. You go to a library catalog and type "Euthanasia" into the search bar. This keyword search tells the database to look for every resource that has the word "Euthanasia" anywhere in the catalog record--in the title, the author, the resource description, etc. The database is simply scanning its records indiscriminately according to the string of letters that you entered into the search bar.
Even a search this simple will likely yield some good results. However, you will also miss a lot of helpful resources by searching this way. Why? Because there are resources on euthanasia that do not have the exact word "euthanasia" anywhere in the record. What if there is a book on euthanasia with a title like Between Life and Death, or Peaceful Passing? A keyword search of "Euthanasia" would not locate either of those books.
However, if those books have been assigned the subject heading "Euthanasia," and you were to run a search using that subject heading, the system would locate those resources in your search results. A subject heading search tells the database that you want everything it has on a particular subject, regardless of what words happen to be in a resource's title or description.
Many books include several LOC subject headings towards the bottom of their copyright page. The copyright page is just past the title page, where the author and publisher information are located. (See Fig. 1 for example).
Subject headings can also usually be found in a resource's catalog record online. When you click on a book's title in Populi, for example, you can find that book's subject headings under "Subjects" towards the bottom of its catalog record. (See Fig. 2 for example). There is also a tab on the library's catalog page entitled "Subjects," which takes you to a full alphabetized list of all the subject headings we have on record. Clicking on any of these headings will show you all the resources that we have cataloged under them in our library.
Subject headings can also be found on the Library of Congress website (id.loc.gov/authorities/subjects). For example, searching "baptism" on this site yields 31 different subject headings related to this topic, each of which offers a list of closely related headings, as well as a complete list of resources (each with their own LOC catalog record) which have been categorized according to this particular subject heading. Neat, huh?
You should search by subject heading when you want to find everything a library or database has on a particular topic. However, because subject headings are so specialized, they are not always effective when you are searching for a range of topics pertaining to one key concept. (If you are researching Caesar's second invasion of Britain and the fall of Rome, to return to an earlier example). In this case, a carefully-honed keyword search would be your best bet (see Lesson 5).
To locate the best subject headings, you might try using the following strategies:
1. If you already have a book you plan to use as one of your sources, flip to the copyright page and see if there are any subject headings listed there. Then search Populi for these headings by selecting "Subject" under the "All Fields" tab above the search bar and then typing the subject heading. You can also find these headings on the "Subjects" page in the library catalog. Other libraries also have ways to limit your searches to subjects, or have a page of linked subject headings.
2. Go to the Populi "Subjects" page and browse for subject headings that look useful. If you are doing a paper on baptism, it is easy to find several subject headings pertaining to that topic on the list.
3. If you have found a book in any library catalog that looks promising, scroll to the bottom of its catalog record and browse the various subject headings there. That should take you to everything else the library has under those headings.
4. Go to the LOC website and look for subject headings there if you are having trouble finding any that apply to your topic. You can find a wealth of information there--sub-topics, alternative search terms, sample resources that have been cataloged under a particular subject heading--all of which you can write down and take to a library catalog or database to aid in your research.
YOUR HOMEWORK FOR THIS LESSON
1. Check out a book which you found by searching with subject headings.
2. Submit a PDF document containing the following information under the "Exercise 3" assignment on the Populi class page: