The tail is the section at the rear end of certain kinds of animals' bodies; in general, the term refers to a distinct, flexible appendage to the torso. It is the part of the body that corresponds roughly to the sacrum and coccyx in mammals, reptiles, and birds. While tails are primarily a feature of vertebrates, some invertebrates including scorpions and springtails, as well as snails and slugs, have tail-like appendages that are sometimes referred to as tails. Tailed objects are sometimes referred to as "caudate" and the part of the body associated with or proximal to the tail are given the adjective "caudal".
A white-tailed deer's tail
Vulpes lagopus (Arctic fox) sleeping with its tail wrapped as a blanket.
Tail-like structure on a female newborn from coccyx protrusion
Lion (Panthera leo)
An appendage is an external body part, or natural prolongation, that protrudes from an organism's or microorganism's body.
A beetle leg