Study of characteristics,identification,classification, and nomenclature of the organism

Taxon is a rank of taxonomic hierarachy. Example as : kingdom is comes in 1st rank and order comes in 4th rank and so on

Each units of classification is known as a taxon
In biology, a taxon ( plural taxa; back-formation from taxonomy ) is a group of one or more population of an organism or organism seen by taxonomists to form a unit.
Each category, referred as a unit of classification,, in fact represent a rank and is commonly termed as taxon.