The "meow" - an imitative onomatopoeia with various spellings - is a vocalization used by kittens to signal a request to their mother. Adult cats do not normally meow to each other, and so the meowing to humans that domesticated cats exhibit is likely partly an extension of the use of this plaintive signal, this time to an unrelated caretaker of a different species. When communicating with humans, adult cats express variations of this tone to demand food or attention, register complaints and convey bewilderment. A slight alteration in tone, pace or punctuation changes the meaning.

While cats occasionally vocalize to one another with purrs, growls, and screams, they generally communicate with one another through body language. When preparing to fight an adversary or to frighten one away, cats can emit long, articulated meows. Most communications recognized as "meow" are specifically for human interaction.

Purring is often understood as signifying happiness.

Cats sometimes purr when they are ill, or during tense, traumatic, or painful moments.

Most cats growl or hiss when angered or feel threatened, which serves as a warning to the offending party. If the warning is not heeded, a more or less serious attack may follow. Some may engage in nipping behavior or batting with their paws, either with claws extended or retracted.

Some cats will snort (exhale sharply) after a determined effort to catch something has fallen short. Cats are also known to make chirping or chattering noises when observing prey, or as a means of expressing interest in an object to nearby humans. When directed at out-of-reach prey, it is unknown whether this is a threatening sound, an expression of excitement or frustration, or an attempt to replicate a bird-call (or replicate the call of a bird's prey, for example a cicada).[citation needed]

While this behaviour was originally viewed as the feline equivalent of song, recent animal behaviorists[citation needed] have come to believe this noise is a "rehearsal behaviour" in which it anticipates or practises the killing of prey, because the sound usually accompanies a biting movement similar to the one they use to kill their prey (the "killing bite" which saws through the victim's neck vertebrae).

A type of chirrup, the chudder[citation needed], is used as a greeting. Tigers also use this sound. Some cats may also grunt when given attention. The grunt appears to always be modulated with a purr, making it a kind of closed-mouth meow of affection. Contented sleeping cats make soft humming sounds, similar to sighs, when petted.

The cry of a cat in heat is called a caterwaul.

Cats in close contact with humans use vocalization more frequently than cats that live in the wild, the reason being that owners respond strongly to cat vocalizations, reinforcing the behavior. Adult cats in the wild rarely vocalize; they use mostly body language and scent to communicate.