What is a Digipak?

Digipak's are often in a "book-type" style, special edition digipaks also often come with special notes and pamphlets which come with the album, these often include details to do with the album (where/who produced it etc), it pays credit to the people involved also. They are an alternative to the classic jewel casing which covered CD's before, and are similar to the style of casing that is used for vinyl records. 

A digipak is the format for a CD case, it is the front and background that goes into the CD. It can contain the song listings, lyrics, information of the band/compilation and of course contain images.

This source of packaging is often used mostly for special edition albums, four panel digipak's are more likely used in singles rather than a whole album. Digipaks are also used for DVD's however not as often as the CD, the Arctic Monkeys latest album "Suck it and See" use this format however it is very plain and bold.

As they are made mostly of cardboard they can be rather brittle and the teeth of the cover often can rip or become easily worn. However as apposed to jewel casing they are less likely to brake or be smashed/scratched.

A four panel digipak would look like this, it is quite plain and simply opens like a book. 

A six panel digipak is a similar idea but usually with more images and information, it is more complex and opens like a leaflet. The CD image also usually reciprocates the images and theme along the digipak.