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 host has requested that the guest respond to say if they plan to attend the party.
RSVP vs. Regrets Only
If the RSVP says, "regrets only," you only need to respond if you are unable to attend. If you don't respond, the host will expect you to be there. Be sure to use the requested method to respond if you can't attend. It's best not to respond if you will attend, as a response may be confusing to the host. Use other methods to express your enthusiasm about attending the event.
How to RSVP
Invitations requiring an RSVP will have instructions how to respond. A formal invitation, such as a wedding invitation, will have an enclosed response card that you can return in its provided envelope. Informal invitations, on the other hand, may have a telephone number, email address, texting address, or social media method to reply, with instructions. Electronic RSVP requests make it easy to respond by either email or links to a site with buttons to accept or decline.
The RSVP should make it clear who is invited. Couples are often named together, sometimes followed by "and family," which would include your minor children. It may indicate you are able to bring a guest, often called a "plus one." If you don't see any indication that the invitation allows you to bring a guest, you should assume it is only for you and anyone else explicitly named.
There may be a blank to write in a number of guests. Check further on the invitation to see what the limits are for a number of guests. If you are considering more than one or two, contact the host to ensure the event can handle the number you are proposing to bring.
When to RSVP
RSVP requests often include a deadline for response, as the host is finalizing numbers for the caterer, event site, favors, and other event details. It's best to respond as soon as possible rather than delaying. The host then may be able to offer invitations to other people who didn't make the first cut for invitations or accommodates extra guests of other invitees.
If you want to attend but are unable to give a definite response before the deadline, it's best to decline. You can contact the host with your regrets and explain what is keeping you from being able to know you can attend. Ask if there is any flexibility but understand if there isn't. The earlier you make this call, the better, rather than waiting until the host has followed up with requests to return the outstanding RSVPs.
Canceling or Changing an RSVP
It is bad form to cancel an RSVP, with exceptions including illness or a death in your family. The host will already have made plans based on your attendance. The time to decline is when you make the RSVP, considering all the factors as to your scheduling, finances, and other opportunities. If you declined the RSVP but discover you can attend the event, contact the host to see if it is possible.
Why It's Inconsiderate Not to RSVP
Many people don't RSVP because they don't want to disappoint the host. This attempt to spare their feelings usually causes more trouble than a simple no. An incomplete list of respondents can cause numerous problems for a host, including difficulty in planning food quantities, issues relating to minimum guarantees with catering halls, uncertainty over the number of party favors, and difficulties in planning appropriate seating, among other things.
Sometimes people don't send an RSVP by the requested time because they are unsure if they will be able to attend and don't want to commit to an answer. If this is your situation, it's best to be honest with the host about your situation. The only way they can help make accommodations for you is if they know you need them.