A CD (compact disk) holds 750 megabytes of information. 
If all of these bits and bytes don’t mean much to you then this is a practical guide for you. These are the basics for how much of your various types of memories will fit on a single CD.
80 minutes of audio
400 slides scanned at 1200 dpi so you could print a good quality 4” x 6”
4,500 4” x 6” photos scanned at 300 dpi
A DVD (digital video disk) holds 4.7 gigabytes (1 gigabyte = 1024 megabytes). In useful terms this would be:
2 hours of video from a video tape (they can hold more but your video quality will be reduced)
20 minutes of video from a video tape saved as an avi file type (for editing your video at home).
1800 feet of film (this is approximate since films were shot at a variety of speeds)
3000 slides scanned at 1200 dpi so you could print a good quality 4” x 6”
30,000 4” x 6” photos scanned at 300 dpi