I spent a number of years of my life working with a card catalog similar to this one. In fact, I spent so much time working with card catalogs that I developed a high-speed way to thumb through a whole drawer of cards if it were necessary to do so. I write about catalogs and include them in the webinars for the BYU Family History Library YouTube Channel. If you do a search on the Channel for the word "catalog," you will find a number of my videos as well as those done by others for the Library. Here is an example:
This is a recurring topic because I frequently find people who do not know that FamilySearch.org even has a "Catalog" and who are also unaware of the catalogs on the other large online genealogy database programs.
A catalog is essentially a way to organize information using systematically, selected identifying criteria. In the old paper-based catalog shown above, The items are arranged alphanumerically thereby allowing the user to "jump" to a catalog drawer. There is a correspondence between the catalog and the way the items in the collection are organized. The overall organization of the collections in the United States usually follows one of the popular categorization systems such as the Dewey Decimal System or that of the Library of Congress. There are other systems used in countries around the world.
The categories selected in any cataloging system are somewhat arbitrary. They usually revolve around pre-selected general categories with some modifications. Individual items usually appear cataloged by subject, author, and title. As computers became more available during the 1970s, large libraries and archives began computerizing their paper catalogs. Unfortunately, they almost always simply took their existing catalog system and transferred it to the computer files. Today, if you walk into a library or archive in the United States, the books and other items in their collections are still in essentially the same order as they were before computerization. For someone like me, who has spent almost my entire life in libraries, finding items on the shelves is fairly easy once I figure out the peculiarities of the individual library.
Catalogs do have their drawbacks. The major drawback is the ultimate limitation of the system. For example, if I am looking for a particular ancestor, I will almost never find him or her listed in any catalog. I must essentially guess which items might contain information about my ancestor. This guessing process is a learned skill and can take years of experience to master. Every time I move to a new library or archive, I have to start all over again learning the particular system used.
As a genealogist, all of the information that is available about your ancestors is locked up in records. Many of these records are in libraries and archives. Consequently, we all have to deal with catalogs.
Online catalogs have their own idiosyncrasies. The basic limitation is that you do not have access to the physical items represented in the catalog so you often cannot tell if you have missed something important. As the video above illustrates, the only sure way to know what is in a library or archive is to "walk the shelves." Those libraries or archives with "closed stacks" will always remain a mystery and no researcher can ever be completely sure that every pertinent item has been found.
The key to learning to use a catalog is practice. You must simply try over and over again to find what you are looking for. There is no other way to find the information. Once you find a book or roll of microfilm, again, you must search the entire book or roll or manuscript or record or whatever.
So, where do we start? I use the FamilySearch.org Catalog (located in the Search tab drop-down menu on each web page) as my basic starting point. I usually start with the places where events in the lives of my ancestors occurred. Then I look through all of the relevant subject headings for a list of the items in the library. If I find what I am looking for, I start all over again. If I do not find what I am looking for, I expand to other websites by using the subjects and titles I find in the FamilySearch.org Catalog. I usually end up with a general Google search for related items anywhere else in the world.
This process might take a few minutes or hours or days or years. I have been looking for some information about certain ancestors for over twenty years now. I make the same searches over and over again because I may have missed something or something new might have been added to the libraries or other repositories. By repeating the searches year after year, I learn more about the library or repository each time I do the search. Most of my major breakthroughs have come either because of newly added records or because I finally think of a class of records I have not thoroughly searched.
In searching on the internet, I find that my searches are never complete because an exhaustive search is impossible. As a genealogist, you may hear a reference to a "reasonably exhaustive search." This term is a holdover from paper-based libraries. Today, given the vast number of websites and resources on the internet, one reasonably exhaustive search could last a lifetime and of course, what you might consider an exhaustive search, might be trivial to me.
Whenever you think you are "done" just wait a little while, go to some classes, listen to some webinars, read some books and you will soon discover that you have only begun to do your searches.