The abbreviation ''cf.'' (short for the la|confer/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 word ''see'' be used to point to a source of information.
In biological naming conventions
, ''cf.'' is commonly placed between the
Genus (plural genera) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses, in biology. In the hierarchy of biological classification, genus comes above species and below family. In binomial ...
In taxonomy, binomial nomenclature ("two-term naming system"), also called nomenclature ("two-name naming system") or binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, both ...
to describe a specimen that is hard to identify because of practical difficulties, such as poor preservation. For example, "' cf. '" indicates that the specimen is in the genus ''
''Barbus'' is a genus of ray-finned fish in the family Cyprinidae. The type species of ''Barbus'' is the common barbel, first described as ''Cyprinus barbus'' and now named ''Barbus barbus''. ''Barbus'' is the namesake genus of the subfamily Barb ...
'' and believed to be ', 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 ", cf. '", 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.
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