Cats use a variety of body language cues to communicate with each other in a positive way. When a cat blinks slowly at another cat, it's a sign of relaxation and trust. This is often referred to as a "cat kiss" and can be a great way for cats to communicate their friendship with each other. When a cat's tail is held straight up or slightly curved at the tip, it indicates that the cat is feeling confident and friendly. Cats will often rub their heads or bodies against each other as a sign of affection and familiarity. Cats that are comfortable with each other will often engage in play behavior such as chasing each other, wrestling, or batting at each other with their paws. Cats that are close friends will often groom each other, which helps to reinforce their bond and remove any unpleasant scents or dirt from each other's fur.