A cat calmer is a product designed to reduce stress and anxiety in cats. These products often contain natural ingredients or synthetic pheromones that mimic the calming scents cats produce. Examples include calming collars, sprays, diffusers, or treats. They aim to create a more relaxed environment for the cat, particularly in situations like moving to a new home, visits to the vet, or exposure to new people or animals. Always consult with a vet before using such products to ensure they are appropriate for your cat's specific needs.