Hi Amanda!
With Disney's PhotoPass service, you may have photographers in the parks capture shots of you and those you are with. The photos will be added onto a PhotoPass card you'll be given by a PhotoPass photographer. You can then use the ID on the card to view your pictures
online (from home once you've returned from your vacation) through a Photo Pass account you'll create, or at various Photo Center
locations at Walt Disney World. The service is without obligation and you pay only for any of the products or prints you wish to order. You can purchase products such as prints, Photo CDs, PhotoCards, calendars, etc.
The Photo CD is a great option, if like me, you find you love so many of the photos from your vacation that selecting which ones to print becomes a challenge. The costs of prints can add up quickly, so for me, the Photo CD is a good value because I get all the photos from my vacation and I can print on my own. If you have a good feeling that you'll make good use of PhotoPass services, then I suggest considering the
pre-arrival special offer for a discounted Photo CD as part of a pre-order package, which acts as a credit towards the order of your Photo CD. Currently, the pre-order offer for the Photo CD is $99.95 (regularly it is $149.95, though price is subject to change).
Hope this help. Please let me know if I can answer any other PhotoPass questions or help with planning your vacation otherwise! Have a magical vacation!