NatGeo says:Cats communicate using at least 16 known “cat words.”Wikipedia says:
Adult cats do not normally meow to each other, and so the meowing to human beings that domesticated cats exhibit is likely partly an extension of the use of this plaintive signal. When communicating with human beings, adult cats express variations of this tone to demand food or attention, register complaints, and convey bewilderment. An alteration in tone, pace, or punctuation changes the meaning, however slight.
While cats occasionally vocalize to one another with purrs, growls, and screeches, 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 vocalizations recognized as “meow” are specifically for human interaction.Cats also lick each other and people (e.g. their owners). Cats lick each other to groom one other and to bond (this grooming is usually done between cats that know each other very well). They will also sometimes lick people for similar reasons. These reasons include wanting to “groom” people and to show them care and affection.
Touching noses is a friendly greeting for cats, while a lowered head is a sign of submission. Some cats will rub their faces along their guardian’s cheek, hands, or ankles as a friendly greeting or sign of affection. This action is also sometimes a way of “marking their territory”, leaving a scent from the scent glands located in the cat’s cheeks. More commonly, cats do something called a “head bonk”, or “bunting”, where they literally bump someone with the front part of their heads to express affection
Do read it all, it is quite interesting