'加入' (jiā rù) is a compound verb meaning 'to join' — typically referring to becoming a member of a group, organization, club, team, or online community. The first character 加 (jiā) means 'to add' or 'to increase', and the second character 入 (rù) means 'to enter' or 'to go into'. Together, they convey the idea of adding oneself into something — entering a collective entity with intention and commitment.

This verb is commonly used in both formal and informal contexts: signing up for a WeChat group, enrolling in a university club, becoming a member of a nonprofit, or even joining a family dinner late. It implies voluntary participation and often requires some form of acceptance or registration. Unlike verbs like '参加' (cān jiā), which emphasizes participation in an activity or event, '加入' focuses on membership status and affiliation with a lasting entity.