During the nineteenth century, the bride and groom would give their friends and acquaintances wedding cards to invite them to their new home. The form and wording of these cards changed throughout the years, but usually they contained the new home address and the days when the bride would be at home to receive the good wishes of anyone who wanted to visit her. At first these cards were an invitation to a banquet during which sweetmeats (usually including the wedding cake) and wine were served, with the announcement of the marriage and the new address of the couple.
In time, this banquet and the invitation to come and congratulate the bride were abolished and the wedding card simply stated the new address and when the couple would come back from their honeymoon. As time went on, these cards became even simpler: at first the address wasn't included anymore, then the date was left out as well and the card sent in a very plain white envelope and then they were substituted by the ordinary calling cards of the bride and groom joined together with a silver tread.
The Household Cyclopedia of Practical Receipts and Daily Wants, published in 1873 says about wedding cards: "though fashions are continually changing with regard to wedding cards, the plainer they are the better. Silver-edged cards, or cards tied together with a silver cord, are quiet and pretty. A much-to-be commended fashion has of late years been largely adopted of dispensing with the use of wedding-cards. When this is so, the friends are at liberty to call as soon as they please after the return from the honeymoon. These various calls, whether by invitation or simply as morning calls, must be returned by the bride and bridegroom; or if that is not possible by the bride and her chief bridesmaid."
The household cyclopædia of practical receipts and daily wants
Marriage Customs Of The World by George P. Monger