Not every dog owner knows that the color of their pet's collar can tell about the animal's character and its needs.
The idea of color-coding dog collars began to develop about 25 years ago in Australia, when a trainer decided to use yellow ribbons and bandanas on dogs to signal to others that the animal needed more space.
Since then, this system has spread to many countries around the world.

Gradually, dog handlers have identified the main colors of collars or leashes and what they can mean.
A red collar, similar to a stop sign, signals that the dog may not be ready for interaction. This does not necessarily mean that the animal is aggressive – rather, it warns that the dog does not want to meet new people and animals on a walk.
Conversely, a green collar indicates that the dog is friendly and open to communication – just like a green “go” traffic light.
A yellow collar, as mentioned above, can warn that the pet needs more space to get used to an unfamiliar environment.
Yellow can also mean that the dog is looking for a new home.
It is customary to put a white collar on blind or deaf dogs.
If you see an animal with such a collar, it does not mean that it is aggressive or unfriendly. The white accessory is a signal that the dog may be scared if you approach it unexpectedly.
Orange color indicates that the dog is comfortable meeting new people, but is not in the mood to communicate with other dogs.
The purple collar serves as a sign to others that the dog should not be fed.