Why do we print ‘RSVP’ in invitation cards?

It is a common practice to write ‘RSVP’ in any kind of invitation card. RSVP is an abbreviation of a French word "répondez, s'il vous plait” which means to reply.

In western countries it is a custom to respond to an invitation extended to somebody. In other words, the invitee is expected to inform the host whether he/she has accepted the invitation and will be attending it. RSVP is also a way of showing courtesy to the host who makes arrangements expecting the invitees to the function. 

Earlier, the practice was that if the invitation was in writing, the response was also expected to be in black and white. There would be a reply card attached to the invitation that can be sent back immediately. With the advancement in technology, the practice of attaching the response card gave way to the practice of giving telephone numbers so that the invitee can be informed just by a call. 

Of late, ‘RSVP’ gave way to the wording “REGRETS ONLY” at the end of the card, whereby the invitee is expected to inform the host about his absence in advance.