Training collars are tools used to assist in the training of dogs. They come in various types, including flat collars, martingale collars, and electronic collars. Each type serves a different purpose, such as controlling pulling on a leash or providing a gentle correction for unwanted behaviors. These collars can help reinforce commands and improve communication between the dog and its owner. However, it's essential to use them responsibly and in conjunction with positive reinforcement techniques to ensure the dog's well-being and promote a healthy training experience.