Save the date cards can take the form of any message medium, and often do. They sometimes correspond in style to the wedding invitations, or they take the form of refrigerator magnets, brochures, postcards, booklets, or tri-fold letters. The medium is up to you, but the shortness of the message usually lends itself well to magnets or small cards.
There are many types of save-the-date. Although a save-the-date is traditionally a card, it can also take the form of magnets, bookmarks, or wedding stationery. Any type of save-the-date can be a meaningful keepsake of your wedding day. They also serve the purpose of giving your guests the first indication of what your wedding will be like and what to expect at the wedding reception.
Some companies offer digital save the date cards as well. What this means is you have the card to use on your computer and you could send them out to any email address that you have. Since almost every household has a computer and an email address, this would be a good way to save money on postage stamps.
If you know what your theme or colors are going to be, you can incorporate that into your save the date cards as well. You can also include your engagement picture if you have one. You can have these cards made at a bridal shop or stationery store. You might be able to get a discount if you order the save the date cards when you order your wedding invitations.
Although wedding save-the-date cards are not part of the etiquette for a wedding, it is wise to make use of them. It allows your guests to be able to set aside time for your wedding in advance. Generally, people would like to know about your wedding as soon as they can, especially if they are keen to attend. Also, if travel arrangements need to be made, then it is best to be informed early.