美国活动产业协会（Events Industry Council，原Convention Industry Council）在专业词表中定义event为：An organized occasion such as a meeting, convention, exhibition, special event, gala dinner, etc. An event is often composed of several different yet related FUNCTIONS. EIC所说的Event是指有组织的活动，如会议，大会，展览，特殊活动，节日宴会等。

Charles Bladen等认为，活动就是临时性有目的的集会。（Events are temporary and purposive gatherings of people. ）活动具有四个特征：（1）临时性（They are temporary in nature）；（2）集体性（They are gatherings of people）;（3）仪式性（They are often displays of ritual）；（4）唯一性（They are, in some sense, unique occurrences）.