RSVP

Do you RSVP?

What exactly does RSVP stand for? Abbreviation of French répondez s'il vous plaît

Synonyms are: reply, acknowledgement, answer & response (All according to Bing)

I have always put RSVP on any invitations I send out. How else will I know if they received the invitation and how many people to expect? I try to come up with a date that gives them plenty of time to check their calendar and decide if they are coming, but I also need to know a little ahead of time to make arrangements. And with technology there are mulitple ways to "RSVP", the usual calling, texting, emailing and of course Facebook.
Still, every time we plan an event, I am reminding/asking "will you be able to come?" It gets very frustrating. Out of 115 invitations I received 43 yes, 17 no. That leaves 55 that did not answer.
So I made an "executive decision", I ordered food for 50 people and if we run out, well then, we run out!