hanamaru
Address someone by name, politely
さん after a name is a politeness ending, like 'Mr' or 'Ms' — never used about yourself.
JLPTN5
name + さん / くん / ちゃん~ san
Mr; Ms; -san (polite name suffix)
Attach さん to someone's name and you are being politely neutral: ゆきさん works for a classmate, a colleague or a stranger, with a given name or a family name. Two softer endings show up among friends and family: くん, usually to a boy or a younger male colleague, and ちゃん, affectionate, for small children and close friends. さま is the formal one you meet in shops and letters. The one rule you cannot break: never put any of them on your own name — say just わたしは ゆきです.
