A digipak is something which is used to hold a CD in for when an artist how released a single. They are sold in shops such as HMV and another purpose of it is to advertise the media product you are selling. It is important that the digipak you create will stand out to audiences and potential customers because you want them to buy YOUR product and not someone else's. It will also help to identify your genre because if you have a heavy metal band with a pretty flower as the cover, people will assume you are more of a soft pop band.
Here is an example of Green Day's digipak. You can see from the colours they use it is a rock band because the colours and what they connote. 