ちゃん is an affectionate suffix added after a name or title. It makes someone sound cute, familiar, loved, or younger/smaller.
It feels similar to English nicknames like “-ie” or “-y”, as in “Annie” or “doggy.”
Common uses:
• Children: warm and cute
• Pets: very common and affectionate
• Close friends or partners: shows closeness or sweetness
• Family nicknames: おばあちゃん means “Grandma,” and おじいちゃん means “Grandpa”
Be careful: ちゃん is not neutral like さん. With someone you do not know well, it can sound too childish, overly familiar, or condescending.
Avoid it in professional settings, with superiors, and with strangers. When unsure, use さん.