Tuning files are important for repeat tunings. They store the inharmonicity measurements and your exact adjustment of the tuning curve. Using a tuning file from an earlier tuning saves you from having to measure the inharmonicity and adjust the tuning curve again. Here are some hints on how to organize and backup your tuning files.
TuneLab Piano Tuner (for iPhone, iPad, iPod Touch):
Tuning files in the iPhone, iPad, and iPod Touch are stored as documents under the app. They are automatically backed up by iTunes whenever you sync your device. But if you wish to manually copy tuning files into or out from your device, then you can use something Apple calls "file sharing". See this page on the Apple website for information on how to use this feature. Tuning files generated by TuneLab Piano Tuner are compatible with TuneLab Pro and TuneLab Pocket, so you can freely copy and use tuning files between these applications.
TuneLab Pro (for Wiondows laptops):
TuneLab Pro offers the option of storing tuning files in the TuneLab folder under the My Documents folder. When you store tuning files, you can store them all in that folder, or you can create sub-folders under TuneLab to form categories, such as Churchs, Homes, and Schools, or Grands and Uprights or whatever categories you like. By using sub-folders you can make it easier to browse through a large number of files. You can create sub-folders when you save a tuning file by clicking on the Create New Folder icon show here:
The subject of backing up documents is covered extensively by others, so I will not dwell on it here, except to say that hard disk crashes do happen. Making a CD or diskette of your TuneLab documents folder every so often is good insurance.