A og collar is a is a piece of material put around the neck of a dog. A collar might be used for control, identification, fashion, or other purposes. Identification tags and medical information is often placed on dog collars. Collars are also useful for controlling a dog manually, as they provide a handle for grabbing. Collars are often used in conjunction with a leash, and a common alternative to a dog collar is a dog harness. Dog collars are the most common form of directing and teaching dogs.