In the Linnaean classification, organisms are placed in hierarchical groups based on appearance.

Organisms in lower groups bear more similarity in appearance.

Each organisms is identified by a binomial scientific name: its Genus and species.

For example, Equus quagga for the Zebra, which also belongs in:

• Family Equidae,
• Order Perissodactyla,
• Class Mammalia,
• Phylum Chordata,
• Kingdom Animalia,
• Domain Eukaryota.

The binomial name for humans is Homo sapiens.