Why does a single record in a library’s catalog need to include author names, publication dates, subject terms, identification numbers, and notes? You might notice a catalog record is chock full of information because it actually brings together several different kinds of information. Some of the fields are describing the item, some of the fields are designed to help you search for it in different ways, and sometimes a separate item record will include information about where one particular copy of a specific book is located in a specific library. When all of this information is present all at the same time, it can be hard to figure out what is what, and that can make it confusing how you are supposed to use all this information all at once. It is easier when you read the record with a single question in mind.
First, verify what the item is. Look at the title, subtitle, and the responsibility statement (the part that names the author, editor, translator, illustrator, or another contributor). Do not think that the largest name on the screen must be the author. An edited collection, a translation, or a report issued by an organization can put different responsibility on a variety of people. Comparing the title, subtitle, and names to the cover or title page of the book can be much more accurate than just looking at the screen alone. Then, take note of the edition statement and the publication fields. The edition can tell you if you are looking at a first edition, revised edition, student edition, or something else. Publication includes publisher, location, date. This is why sometimes you see two items with the same or similar titles; they could have different chapters, pages, content, etc. You can double check by ISBN, but that should be used in conjunction with the edition, rather than instead of.
Instead of reading a single catalog record, compare at least two. Search for the title and choose one item and choose another. Only look at these four fields: who is responsible for the work, what edition, when published, and the ISBN. Why are the two records separate? The edition might not be the same, or the book might be a different kind of book (paperback versus hardback, or a newer edition with more or different content). This allows you to know which fields matter, and which might not as important to you.
Once you are certain what the item is and know if the edition is what you are looking for, you want to look at what fields are there to help you find the work. There will be headings for keywords and subjects. A keyword is any word that might be in the title of the book, the description, note, or even somewhere else in the fields. If you use too many keywords you may not get the right results. There will also be a controlled subject (often a subject heading) field, which is a term used by the system to describe the work. This is often helpful when using a different word for a topic. For example, there are a number of books on the Civil War, written by a number of different authors. You might choose one to look at for more research, follow the subject heading to find a few others that might be useful.
Location information can sometimes be found in the main bibliographic record, but more often than not, it is found under holdings or item. This is also when you would find your call number, the library or collection name, availability (if in stock or not at all), barcode, and status (if it is checked out, or missing, or being repaired, etc). The location is where you will see what your call number is, so you can find it on the shelf when necessary. The status of an item will tell you if the book is checked out, if the item is damaged or missing or not, etc. One bibliographic record can have several items if it is a book that the library has two or more of.
Finally, you have the item and the location information, but before you can fully trust a record, you need to verify what the book is, what edition of the book it is, and if it is where it should be. Look at the call number to see if it matches with the book itself, or at least if it matches the book’s spine. Now you know how to read a catalog record! It is still a little confusing at first if you try to look at the catalog record as a whole, but if you look at each field individually, you can quickly find the information you want.