Is BTFS a file storage or file transfer system?

Both. BTFS is a file system encompassing the dual nature of storage and transfer. Users can ensure some storage persistency by pinning their files to their BTFS nodes. When other nodes in the network request the file, that file duplicates via the requesting nodes. BTFS also allows the efficient and secure transfer of files between nodes located across regions. This makes BTFS an ideal choice in file transfer.