Cats communicate for a variety of reasons, including to show happiness, express anger, solicit attention, and observe potential prey. Additionally, they collaborate, play, and share resources. When cats communicate with humans, they do so to get what they need or want, such as food, water, attention, or play. As such, cat communication methods have been significantly altered by domestication. Studies have shown that domestic cats tend to meow much more than feral cats. They rarely meow to communicate with fellow cats or other animals. Cats can socialize with each other and are known to form "social ladders", where a dominant cat leads a few lesser cats. This is common in multi-cat households.

Cats can use a range of communication methods, including vocal, visual, tactile and olfactory communication. Up to 21 different cat vocalizations have been observed. They use visual signals, or body language, to express emotions like relaxation, fear, and aggression. Cats use several types of tactile behaviors to communicate, such as grooming or biting each other. They also use olfactory communication, such as marking their territory via urine.

Cat vocalizations have been categorized according to a range of characteristics. In 1944, Mildred Moelk published the first phonetic study of cat sounds and classified the 16 different vocal patterns into three main classes:

Moelk used a phonetic alphabet to transcribe or write down the different sounds. She claimed that cats had six different forms of meows to represent friendliness, confidence, dissatisfaction, anger, fear, and pain. Moelk classified eight other sounds involved in mating and fighting.

Brown et al. categorized the vocal responses of cats based on the behavioral context. These contexts include situations such as the separation of kittens from mother cats, instances of food deprivation, pain responses, occurrences before or during threatening or aggressive behaviors (e.g., disputes over territory or food), episodes of acute stress or pain (e.g., routine prophylactic injections), and instances of kitten deprivation. Less common calls from mature cats included purring, conspecific greeting calls or murmurs, extended vocal dialogues between cats in separate cages, "frustration" calls during training, or extinction of conditioned responses.

Owens et al. categorized cat vocalizations based on their acoustic structures. There are three categories: tonal sounds, pulse sounds, and broadband sounds. Tonal sounds are further categorized into groups of harmonically structured sounds or regular tonal sounds. Pulse vocalizations are separated into pulse bursts and hybrid pulse bursts with tonal endings. Broadband sounds are separated into four groups: non-tonal broadband sounds, broadband sounds with tonal beginnings, broadband sounds with short tonal elements, and broadband sounds with long tonal endings.

Miller classified vocalizations into categories according to the sound produced: the purr, meow, chirrup, chirp, call, and growl/snarl/hiss, and the howl/moan/wail.

The purr is a continuous, soft, vibrating sound typically made with rapid muscle contractions in the throat by most species of felines. However, the reason why cats purr is still uncertain. Cats may purr for a variety of reasons, including when they are hungry, happy, or anxious. In some cases, purring is thought to be a sign of contentment and encouragement for further interaction. Purring is believed to indicate a positive emotional state, but cats sometimes purr when they are ill, tense, or experiencing traumatic or painful moments such as giving birth. It has also been suggested that purring can act as a soothing mechanism and can promote healing.