1. Helping you clean yourself. After kittens are born, their mothers lick them with their rough tongues. The kittens learn to clean themselves with their tongues from their mothers, so when a cat licks you, it may be trying to clean you and groom your fur. Cats helping their trusted companions clean themselves is a sign of trust.
2. Expressing affection. Licking is a sign of affection and intimacy. Besides learning to clean themselves with their tongues from their mothers, cats also understand that licking is a way of expressing love. Licking you is a way of expressing closeness and affection.
3. Covering up scent and possessiveness. To demonstrate ownership, cats will leave their scent on objects they are approaching. For example, cats have glands in their cheeks and will rub against objects or people to leave their scent. Licking saliva left by people is also a form of scent marking. Cats use the scent on their tongues to mark their territory and warn others not to approach or intrude.
4. Seeking memories. After weaning, kittens will seek out the comfort and security they felt when suckling from their mother.
5. It could be due to anxiety. When cats feel stressed or anxious, they may exhibit uncontrollable compulsive grooming behavior. They may lick fabric, plastic, or people to relieve stress. If owners notice excessive licking in their cats, they need to investigate the cause of the cat's anxiety and consult a veterinarian.
6. You might really smell nice. The salt, certain trace elements, or oils in human sweat can make cats smell "smell good," and some creams can also attract cats, but they are harmful to cats, so be careful not to let your cat lick them.
7. A social interaction. Cats lick each other, especially on areas they can't easily reach themselves, such as the top of their heads and ears. This is a friendly interaction. A cat licking you is a way to strengthen the bond and a form of interactive social interaction.
8. It wants you to play with it. When the owner is too busy and neglects the cat, it will come over and lick or rub against you to get your attention and want you to play with it.
9. Gathering Information. Cats learn where their owners have been and what they've done by licking their bodies to detect their scent. Cats want to know if you've been with other cats outside, and if so, they can smell it and may get angry with you.
10. It's sick. If your cat licks your hands and feet, it could be because it's sick. Since cats can't speak, they lick their hands and feet to get your attention and hopefully notice anything unusual when they feel unwell.
11. To comfort you. If you're unhappy or angry, a cat licking you is a way of expressing comfort. Cats hope to cheer you up by licking you. You can pet the cat's head to relieve stress and ease your anxiety.
12. Your cat is hungry. If your cat licks you at mealtimes, it's trying to remind you that it's time to feed it. If your cat licks you particularly enthusiastically, check if its food and water bowls are empty. 
The meaning of a cat licking different parts of its body:
1. Licking your hand. When a cat licks or gently bites its owner's hand, it's a sign that the cat is hungry or craving food and wants it from its owner. If the owner frequently feeds the cat treats by hand, the cat will develop a conditioned reflex.
2. Licking your face. When a cat licks your face, or even your lips, it's definitely not accidental; it's a way for the cat to express affection. When kittens are young, their mothers often lick them like this, and the kittens find it comfortable and surrounded by love.
3. Frequently licking a certain part of its body. If your cat frequently licks a certain part of its body, you should check if that part is injured. If it is not injured, then the cat is likely feeling scared and anxious.
4. Frequent licking of the genitals. If a cat licks its genitals for an extended period of time, and the genitals are abnormally colored or have a large amount of discharge or pus, it indicates that the genitals may be inflamed.
5. Licking excrement. If your cat likes to lick its excrement, it is very likely that it is suffering from pica due to a deficiency in trace elements. Urine contains nutrients such as minerals, proteins, and sugars.
