Came across a forum where people asked what does RSVP means.
We all know that it means something to response to an invitation, however, not the
full meaning. Interesting to find out that we need to reply regardless we are attending
or not attending... Had you replied to your friend wedding RSVP? =P

The meaning of the terms : RSVP

The term RSVP comes from the French expression "répondez s'il vous plaît", meaning "please respond". If RSVP is written on an invitation it means the invited guest must tell the host whether or not they plan to attend the party. It does not mean to respond only if you're coming, and it does not mean respond only if you're not coming (the expression "regrets only" is reserved for that instance). It means the host needs a definite head count for the planned event, and needs it by the date specified on the invitation.