Depends how much data and what your doing with it.
Obvious one is a Memory Stick (Flash Memory)
They are available in a range of sizes form 128Mb - 32Gb
They are cheap and fairly robust.
If you want something a bit bigger you can go for a portable harddrive available in 120Gb - 500Gb generally.
Alternatives:
CD-R
CD-RW
DVD-R
DVD-RW
Flash Memory
Portable Harddisk
External Harddisk
Transfer rate.
slowest device for data transfer
Storage device
If the data is not in the cache already the storage device sends the data requested to a cache, which results in a wait stage, when the data has been copied to the cache it can then be transferred to the requesting device. Caches have faster transfer rates than that of your typical storage devices, thus when the request is sent to the cache for the data it can be transferred a lot faster than if it is transferred from the storage device, the data is then also not deleted immediately so if the data is required again, there is no wait stage and the data can be transferred immediately.
To transfer files from one data storage device to another in Windows 8.1, connect both devices to your computer. Open File Explorer, navigate to the source device, and select the files you want to transfer. Copy the files by right-clicking and selecting "Copy," then navigate to the destination device, right-click in the desired location, and select "Paste." The files will then be transferred to the new device.
output
storage is store a data , device is drive (data drive) eg harddisk pendrive.
The Device we can used to store data by the Computer,it is know as Storage Device.
Secondary Storage
To back up data, transfer media, install applacations, store files with out storge devices your coumputer is useless
a cd
As far as I know, no storage device is an input device but data can be inputted on to it. Unless a program is running from a storage device and transfers data to another then it might be considered an input device but that's it.