There is the outer envelope, inner envelope, invitation card, reply card (RSVP) and reception card. You can also include other enclosure cards such as map cards and hotel accommodations. Invitation, reply card and reception card should be printed in the same method and on coordinating papers.
The outer and inner envelope:
The outer envelope has been used throughout history to ensure that each guest receive a pristine envelope. Even if the outer one has been torn or damaged in the mail the inner one will be flawless. Since mail isn’t carried around by horses any more, this isn’t a concern today, however, outer-inner envelopes are still widely used. It is a part of tradition and it will give your wedding invitation suite a few extra fancy points. The outer envelope includes all of the information the postal service needs for delivery: stamp, guest address, and return address. The inner envelope should have the names of the invited guests in the household (including children, whose names do not appear on the outer envelope).
The invitation card:
Invitation is the centerpiece of the invitation set. It should include all the most important information about your wedding including time, date and location and state the dress code: is the attire formal or casual. Invitation also gives your guests an idea about the theme and color choices of the wedding.
The reply card (RSVP):
RSVP card will let you know how many of your invited guests are coming and are they bringing a plus-one to your wedding. It has its own self-addressed return envelope. It can also be printed like a postcard. You should put stamps on RSVP envelopes (or postcards), so your guests are more likely to quickly send it back.
A reception card:
Reception card is useful when the reception will be at a different location than the wedding. It should include time, address and all the other details related to reception. Reception card is smaller than the invitation, but it is printed on the same stationery and written in same style. Reception details can also be printed on invitation, but just like with the envelopes, including the reception card will give your wedding invitation suite a few extra fancy points.
Other enclosure cards:
Map cards and/or hotel accommodations. Don’t leave guests to Google maps when it comes to getting to your wedding on time. Include a map with directions to your venue. You don’t have to send accommodation cards to everyone, just to out-of-town guests. If you’re covering guests’ accommodations, it’s proper etiquette to indicate that on the card.