1. Active and curious: Happy kittens are usually active, curious and full of energy. They will actively explore the surrounding environment, play and chase toys.
2. Good appetite and weight: Happy kittens will have a good appetite and keep a proper weight. They will eat normally and digest well.
3. Socialization and interaction: Happy kittens will actively seek to socialize with people and other pets. They will approach people actively, rub, purr and show friendly body language.
4. Calm and relaxed: Happy kittens will feel calm and relaxed. They will have a normal sleep pattern, and their bodies will relax during rest, with no signs of nervousness or alertness.
5. Good hygiene habits: Happy kittens will maintain good hygiene habits, including self-cleaning, using the litter box to go to the toilet and keeping their hair clean.
It should be noted that each cat has different personality and behavior habits. Therefore, if you notice that the kitten's behavior has changed significantly compared with the past, or there are other abnormal symptoms, it is recommended to consult a veterinarian for further evaluation and diagnosis.