The guest list includes royalty, members of the charities Prince William and Kate Middleton are affiliated with, heads of state and friends of the future King and Queen of England.
The invitation is a white card with gold lettering and gilded edges and reads:
The Queen to invite
(the recipient of the invitation)
to the Marriage of
His Royal Highness Prince William of Wales
Miss Catherine Middleton
at Westminster Abbey
on Friday, 29th April, 2011 at 11:00 a.m.
The invitation is decorated with Queen Elizabeth II's insignia in gold.
The dress code for the wedding asks guests to wear military uniform, a tailcoat or a business suit.
An RSVP card and envelope were not included and guests were asked to mail their response, as is the formal custom, via a letter or note to a specific address listed in the lower left corner of the wedding invitation.
Of the 1,900 guests invited to the wedding ceremony, 600 were also invited to a reception following the service at Westminster Abbey, hosted by the Queen at Buckingham Palace.
300 of these guests are invited to a dinner hosted by Prince William's father, Prince Charles, the night of the wedding, and also being held at Buckingham Palace.
Prince William and Kate Middleton have decided not to release the invitations to either reception since they are private events.
The wedding invitations were mailed on February 16 and 17.
More on Royal Weddings:
Windsor Weddings: Queen Victoria & Prince Albert to Kate Middleton & Prince William
Royal Wedding Ceremony: Who's Officiating, What Kate Will Wear and How She'll Get to Westminster Abbey
Kate Middleton's Wedding Dress: Britain's Top Designers' Picks
Royal Engagement Rings: 11 Stunning Rings Worn by Princess Brides
Royal Wedding Dresses: A Look at Some of the World's Most Famous Wedding Gowns