Ephemeral storage is a temporary storage for storing data such as cache, buffers, swap volume, session data, etc. For example, when you create an AMI of your instance's current state, it will contain everything in what we call as ephemeral storage. This ephemeral storage is replicated to EBS volume automatically by AWS to prevent data loss. The instance launched using this AMI will contain everything in normal instance store volume, the volatile temporary storage that only exists during the running lifetime of the instance.
