An instance refers to a Nova instance. An instance can be created from an image or a bootable volume.
An instance is a live or running version of the image or the bootable volume, from which you have created the instance.
When you create an instance, memory, a fixed IP address, and basic storage are allocated to the instance.
By default, instances are created on ephemeral storage within the hypervisor. If persistent storage is required, you may attach volumes to the instance for block storage.
You can deploy one or more applications on an instance.