兴趣 (xìngqù) is a noun meaning 'interest' or 'hobby' — a feeling of wanting to know or learn about something, or an activity you enjoy in your free time. It differs from 爱好 (àihào), which is more active and often used as a verb ('to like, to be fond of'), while 兴趣 is purely a noun. 趣味 (qùwèi) emphasizes the quality of being fun or engaging, not a personal interest.