Library of Congress subject headings are like tags that help you locate books and other materials at the library. Just like when you look something up online, the Library of Congress uses subject headings to organize information so you can find it more quickly. For example, if you're looking for books about cats, you can look up the subject heading 'Cats' and get a list of all the books the library has about cats. It's like having your own personal librarian who helps you find just what you're looking for!