What's a Controlled Vocabulary?
... controlled vocabulary is a carefully selected list of words and phrases, which are used to tag units of information (document or work) so that they may be more easily retrieved by a search. Controlled vocabularies solve the problems of homographs, synonyms and polysemes by a bijection between concepts and authorized terms. In short, controlled vocabularies reduce ambiguity inherent in normal human languages where the same concept can be given different names and ensure consistency. [from Wikipedia]
Why Do Libraries Use Them?
Believe it or not, libraries use these specialized lists of words to make searching easier. Because the words used are consistent across libraries, once a searcher knows the proper terms, s/he can quickly find what s/he wants in any library catalog.
In online catalogs, they also provide a convenient way to link similar books to each other.
What Kind does Morris Use?
Morris Library's catalogers currently use the Library of Congress Classification system to organize books.
In the past, they used the Dewey Decimal System.
The various online databases available through the library use their own controlled vocabularies to sort content.
But regardless of the specific system, all of the databases and catalogs offered through Morris Library apply controlled vocabularies with links that searchers can use to find what you need and speed his/her research.
Let's say that I want to learn more about the Soviet Union's space program during the Cold War.
I got something. Yay!
But there's only 9 results and not all of them look good to me. I bet I can do better.
Check the Topics
Time to pop open the best result, which is the first one in this case.
I check the "Topics" listed to see terms what the catalogers who put this book in I-Share assigned to it.
How in the World...?
What the heck is that? I never would have come up with those words in a million years. Why the heck is that the "Topic"?
That's the topic because that's the phrase that the librarians who maintain the Library of Congress subject headings decided should be used. To keep catalogs consistent, the catalogers who listed this book picked and applied that term from the controlled vocabulary list the Library of Congress creates.
It may be confusing, but I can use the controlled vocabulary to my advantage. I click on the "Soviet Union" part of "Astronautics -- Soviet Union" to pull up all the books associated with that topic.
I like what I'm seeing here. There are more books and they're much closer to what I want to learn about.
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