Device and Cloud Storage
Any content you purchase from Amazon for you Kindle is securely stored remotely on Amazon’s servers; the content is said to be stored in the cloud and so it is known as cloud storage. The idea is to allow you to access your content from anywhere, not just on your home computer or Kindle. So if for instance you happened to have a problem with your device you could still retain your data.
All your music, books, newspapers, and apps are stored on the cloud storage and are synched or copied to your device. Depending on your Kindle, you get anywhere between 4GB and 16GB of storage on your Kindle.
Cloud Drive ...