Secure erasing of files or disks being a primary requirement for your solution, you should use this tag.
Wiping is the process of permanent data erasure: files are not simply "deleted", but overwritten using random/garbage patterns, so data recovery should be impossible, and even forensics specialists should have no chances. For more details on the topic, please follow the linked Wikipedia articles.
Where should this tag be used?
Obviously when looking for a tool to securely delete files or media. Good examples include software to prepare mobile devices for re-selling, where one usually doesn't want private information to remain on the device.