Volumes are network-based block devices that provide additional data storage for Droplets. You can move them between Droplets, create disk images of them, and resize them at any time.
Volumes cost $0.10 per GiB per month and range from 1 GiB to 16 TiB (16,384 GiB). Charges accrue hourly for as long as the volume exists.
You are charged for volumes whether or not they are attached to a Droplet.