In its simplest form Cloud Storage allows a user to store files via the Internet, and to access them from anywhere. There is a single point of access, via a device, such as a smartphone, tablet, PC / Mac software, or a web browser based interface. Cloud Storage providers will usually have multiple methods of accessing files via various devices.
The cloud itself consists of multiple, distributed, interconnected hard drives that are linked via the internet. The location and configuration of the resources is not of concern to the general user.
The amount of storage available is flexible and scaleable to the users requirements. Unlike a local storage solution that is restricted by physical drives.
Cloud based services provide data security with mirroring and automatic backup. The advantage over local storage is that there is less risk from physical damage, or major system failures.
A restriction on the use of cloud based storage is the speed of the internet connection available to the user. A slow or unreliable connection combined with a lot of data can make cloud storage unworkable.