In most team matches, only one competitor per team is allowed in the ring at a time. This status as the active or legal wrestler may be transferred by physical contact, most commonly a palm-to-palm "tag" which resembles a high five.
The team-based match has been a mainstay of professional wrestling since the mid twentieth century, and most promotions have sanctioned a championship division for tag teams.
The term "tag team" has since become used in common parlance to describe two or more people who alternate or cooperate in participation in an activity, and "tag-teaming" to describe the act of alternating with an ally, e.g. a couple tag-teaming in an argument with another person.