Removable Drives - Removable drives are typified by the venerable Iomega "ZIP" drive. Today, removable disks are more likely to be available as a USB drive. The USB 2.0 interface is reliable and very fast. 

USB Thumb Drives / Memory Sticks - Small memory based "drives" are available with reasonable capacities (e.g. 4gb).  These devices are relatively slow but may certainly be used as a backup device. NOTE - most "Memory Stick" devices have very low access speeds.  Saving to a "Memory Stick" can take 10 to 20 times as long as saving to a real disk.  All of our backup programs have an option to save the data to the main drive and then make a copy to a second location (i.e. make a copy to the "Memory Stick").  This should be done when using a slow device.

CD and DVD Disks - Most modern PC's include a CD or DVD writer.  The CD and DVD media is quite reliable - though slower than a removable disk drive. See the article How do I save the Backup to CD's or DVD's? for additional information.

Networked Drives - If you have multiple PC's you may also save the backup to a drive on another machine. We recommend that you create a mapped drive to the remote machine for this purpose.

Diskettes - While diskettes may be used, they are virtually obsolete and far from ideal. The capacity of a diskette is quite limited. However our backup files will allow the backup to 'span' multiple diskettes. In our experience, diskettes fail more often than other media. It appears as if the failure is directly related to the importance of the data on the diskette.

Regardless of the media chosen, we recommend that you try to use media which is large enough to accomodate the backup file in it's entirety if possible. This is not mandatory but it does make operations much easier.