Define a taxon. With some examples of taxa at different hierarchical levels.

 A taxonomic unit in the biological system of classification of an organism is called a taxon (plural taxa). For example a phylum, order, family, genus, or species represents taxon. It represents a rank. For example, all the insects form a taxon. The taxon of the class category for birds is Aves and taxon of the Phylum category for birds is Chordata. The degree of relationship and degree of similarity varies with the rank of the taxon. Individuals of a higher rank, say Order or Family, are less closely related than those of a lower rank, such as Genus or Species.