Many couples ask for copies of their wedding pictures on a CD or DVD. This seems like a good idea because they are then free to print images as they wish without significant additional expense. A consequence of this is that wedding photographers generally charge a high price for the high-resolution electronic media.
In practice however, a CD or DVD may not be such a good medium to use for storing unrepeatable wedding images. The data may fade from the disks after a period of years. Manufacturers often quote figures of 25 years or so for the usable life of data stored on their disks. However, the length of time before the data fades may depend in part upon the speed at which the disk was written, the power of the writing laser, and the conditions under which the disk is stored. It is not unknown for disks to become unreadable after a period as short as five years.
Another consideration is the rate at which digital storage technology progresses. It is very unlikely that anyone will have the means of reading current CDs or DVDs in five years - so forget 25 years! Current technology is already being replaced with the incompatible Blue Ray system and it will surely not be too long before something better comes along. Wedding photographs stored on such media would therefore have to be transferred to each new technology as it emerged.
Although many couples have their own computers and printers, the reality is that they will in most cases be unable to print good copies of their wedding images from a CD or DVD. Cheap paper and inks may be used, and colour control is more or less lost on unprofiled printers. Alternatively, the electronic images may be taken to a high street retailer which will print selected images for a relatively low price. The prints from such sources may be variable at best. Try printing the same image on separate occasions and compare the results.