In zoological nomenclature, the valid name of a taxon is the correct scientific name for that taxon. The valid name must be used for that taxon, regardless of any other name that may currently be used for that taxon, or may previously have been used. A name can only be valid (or invalid) when it is an available name under the International Code of Zoological Nomenclature (ICZN); if a name is unavailable, then it cannot be considered either valid or invalid. In contrast, a name which is available but not the correct name for a taxon is known as an invalid name. There are two categories of invalid names.

Subjectively invalid names

Subjectively invalid names are names that have been rendered invalid by individual scientific judgement or opinion. Taxonomists may differ in their opinion, and names considered invalid by one researcher may be considered valid by another. They include:

Objectively invalid names

Objectively invalid names are names that have been rendered invalid for indisputable reasons. These names are universally accepted as invalid, and are not merely a matter of individual opinion, as is the case with subjectively invalid names. They include:

Different rules for botany

Under the International Code of Nomenclature for algae, fungi, and plants, the term validly published name has a different meaning that corresponds to zoology's available name. The botanical equivalent of zoology's term "valid name" is correct name.