Cf.

The abbreviation cf. (short for either Latin confer or conferatur, both meaning 'compare') is used in writing to refer the reader to other material to make a comparison with the topic being discussed. Style guides recommend that "cf." be used only to suggest a comparison, and the words "see" or "vide" be used generally to point to a source of information. In Italian, the abbreviation "cfr." (confronta, 'confront') is more common than "cf." is.

Biological use
In biological naming conventions, cf. is commonly placed between the genus name and the species name to describe a specimen that is hard to identify because of practical difficulties, such as poor preservation. For example, "Barbus cf. holotaenia" indicates that the specimen is in the genus Barbus and believed to be Barbus holotaenia, but the actual species-level identification cannot be certain.

Cf. can also be used to express a possible identity, or at least a significant resemblance, such as between a newly observed specimen and a known species or taxon. Such a usage might suggest a specimen's membership of the same genus or possibly of a shared higher taxon. For example, in the note "Diptera: Tabanidae, cf. Tabanus", the author is confident of the order and family (Diptera: Tabanidae) but can only suggest the genus (Tabanus) and has no information favouring a particular species.

Numismatic use
Among numismatists (coin collector-research specialists), cf. may be used in references on the paper and/or online coin identification information meaning "compare to". It is common for abbreviations of listings in trusted coin catalogues or sales from certain online auctions to be cited when identifying a particular coin. If the specimen in question is not an exact match but comes close to a known source, cf. may be used.