参加 (cān jiā) means to participate, attend, or take part in. It covers attending events (参加婚礼, attend a wedding), joining competitions (参加比赛, enter a competition), and becoming a member of groups (参加组织, join an organisation). It is more active than 出席 (chū xí, to attend formally) and is the most common everyday word for participating in activities. Related: 参与 (cān yù) is a slightly more formal synonym.