Invitations for social events are often marked by the initialism R.S.V.P. This acronym represents the French phrase, “répondez, s’il vous plaît” meaning “please reply” in the English language. This means that the person that gave you the invitation has requested you let them know whether or not you accept the invite.
In many Western cultures, Etiquette rules require that you respond promptly, frequently the same day, upon receiving a formal, written invitation. From a practical perspective, this allows the host of the wedding, dinner party or other event to know how many people to anticipate so they can purchase food and drink accordingly. Perhaps even more importantly is the simple courtesy of addressing the person that was nice enough to invite you. Even in cases where you are unable to attend the event, a prompt response is always appreciated.
The way that you respond to the invite will depend largely on the medium through which it was received. For example, wedding invitations often contain a response card. On this card, you can indicate whether or not you will attend the event and how many people you anticipate in your party. Once you receive the invite, it is expected that you complete the card and mail it back to the sender right away. Invites for less formal events, such as children’s birthday parties, may ask recipients to R.S.V.P. via phone. As a general rule of etiquette, written invitations require written responses.
A more recent trend in event invitations is the “regrets only” notation. This means that the event host will automatically count you among the attendees unless you indicate otherwise.