Humane societies and rescue organizations recommend that dogs and cats wear these tags, which contain information to enable someone to contact a stray animal's owner.
Some people object to pet id tags because of the jingling noise they make as their animals move. A collar-mount tag, which is riveted, flat, to a collar's surface is silent and therefore avoids this problem. Other people use a tag silencer to enclose the loose tags in a small neoprene pouch.
The resemblance of human identification tags to this method of display led to human tags being called dog tags, such as the metal identification tags worn by members of the US military on a chain around the neck; see dog tag (identifier).
Some organizations recommend not putting a pet's name on an ID tag because, in an ownership dispute over a stray dog, the original owner could use the pet's name to demonstrate that the pet recognizes the name and therefore has an association with that owner. Others believe that a lost pet might feel more comfortable if strangers call it by its own name, so the name should be on the tag. Also, if a stray dog slips out of his collar, or is skittish, there is a greater chance of controlling him if his name is used.
Metal tags usually have their information embossed or engraved onto, or stamped into, their surfaces. The characters created by embossing or engraving are made by removing some of the tag's surface and are not as deep as stamped characters, which are made by stamping the tag with a metal die. Stamped tags are therefore more durable.
The most common metals used for pet tags of are aluminum, stainless steel, and brass. Aluminum is the least durable of the three.
Plastic chips can be etched or printed, come in many colors, and are often highly reflective to make the dog more visible if it gets loose and runs into the street after dark.
Microchip implants, tattooing, and registering the dog's license number, microchip information, and tattoo number with lost-pet registries are good backups to identify stolen pets or strays found without ID tags.