It's very important that you backup your VirtualDJ database on a regular basis so that you do not loose the information contained in it if your computer is damaged, lost or stolen or its hard disk fails, gets corrupted, wiped by a virus, etc.
Your VirtualDJ database contains BPM, comments and other information for your songs.
The VirtualDJ database can be found in My Documents\VirtualDJ on PC and /users/YOURNAME/Documents/VirtualDJ or /users/YOURNAME/Library/VirtualDJ for new installations of VirtualDJ v7.0.3 and above on Mac.
Your VirtualDJ folder also contains your playlists, track play history and any custom skins, effects and other plugins that you have installed. You should also back these up if they are important to you. If you are NetSearch user (Premium Member), you should also backup the Cache folder that contains your cached songs that you have downloaded.
If you have customised any mappings for MIDI controllers or your keyboard, these can be found in the Mappers folder.
If you are using external drives, you should also backup the database found at the root of each external drive.
Please ensure that you backup your entire music collection.
Make sure that you copy your backup to DIFFERENT media from what you normally use, e.g: A USB flash drive or backup external hard disk, and preferably keep it in a separate location. Keeping two separate backups is advisable (One to take with you to your gig for emergency use, and another to keep at home.)