A dog collar is a strap or band that is worn around a dog's neck. It serves multiple purposes, including attaching identification tags, controlling the dog during walks or other outdoor activities, and providing a means of restraint. Collars can also be used to attach training devices, such as shock or vibration collars, that help teach dogs obedience and good behavior. Additionally, some collars are designed to prevent dogs from pulling on their leash, promoting better behavior during walks. Overall, dog collars are an important tool for responsible dog ownership, providing a way to keep dogs safe, under control, and properly identified.