The term "RSVP" is an acronym derived from the French phrase "Répondez s'il vous plaît," which translates to "Please respond." It is commonly used in invitations to request that the invited guests confirm whether or not they will attend an event, such as a wedding, party, or meeting. By responding, guests help the host plan accordingly for the number of attendees.
The term "RSVP" originates from the French language, where "répondez" means "respond," and "s'il vous plaît" means "if you please." It has been adopted into English usage primarily in the context of formal invitations.