Backup

Cloud /Offsite Backup:
Also known as online backup, is a stratagem for backing up data that involves transferring a copy of the data over an exclusive or public network to an off-site server. The server is usually hosted by a third-party service provider, who charges the backup customer a fee based on capacity, bandwidth or number of users.

Network Attached Storage (NAS)
Are file-level computer data storage attached to a computer network providing data access to a diverse group of clients. NAS not only operates as a file server, but is specialized for this task either by its hardware, software, or configuration of those elements. NAS is often manufactured as a computer appliance – a specialized computer built from the ground up for storing and serving files – rather than simply a general-purpose computer being used for the role.

External Hard Drive
Is a portable storage device that can be attached to a computer through a USB or wireless. External hard drives typically have high storage sizes and are often used to back up computers or serve as a network drive.