The classic definition of the purpose of a library catalog is that of C. A. Cutter, who stated that the "objects" of a catalog were:

• To enable a person to find a book of which either:
• the author is known
• the title is known
• the subject is known
• To show what the library has:
  • by a given author
  • on a given subject
  • in a given kind of literature [poetry, drama, fiction].
• To assist in the choice of a work:
  • as to its edition (bibliographically)
  • as to its character (literary or topical).