RSVP is a French phrase meaning
RSVP is a French phrase meaning "please reply."

If you receive a dinner invitation, the basic rule is to reply using the same format and tone of the invitation. For example, a mailed formal invitation should be accepted with a formal RSVP message sent by mail. The only exceptions to this guideline occur when the host specifically requests your response in a certain format.

Formal Acceptance

When you accept a formal invitation to dinner, your response should mirror the original invitation. The names should be written exactly as in the invitation. Include the date and time in your response to guarantee you have the correct information about the event. For example, write, "Mr. and Mrs. John Doe accept with pleasure the kind invitation of Mr. and Mrs. Tom Smith for dinner on Saturday, twelfth of September, at six o'clock." If the invitation came with an RSVP card, you may submit that in lieu of writing a formal acceptance.

Casual Acceptance

If the invitation is not formal, accept in the same manner and tone the invitation was made. For example, if a friend sends you an invitation by text message, you can accept by text message as well. Even with casual invitations, consider mentioning the date and time in your acceptance message to ensure your information is accurate.