File corruption after USB transfer means the copied data doesn't match the original source file, making it unreadable or unusable by applications. This occurs because the data transfer process was interrupted or errors occurred during the bit-by-bit copying process. Unlike successful transfers where data is moved exactly, corruption happens when some bits are lost or altered due to transmission issues between the source device and the destination storage via the USB connection.

Common examples include a photo transferred from a camera to a computer appearing only partially rendered with garbled sections, or an important document becoming unopenable after being moved via USB drive. These scenarios frequently occur during everyday file sharing between personal computers or when migrating data from older devices like cameras or external hard drives using USB cables or flash drives.

Corruption can stem from physical damage to cables/ports, sudden disconnections during write operations (like unplugging without "ejecting"), incompatible or failing USB hardware, or device driver malfunctions. While USB offers convenience, its susceptibility to these interruptions is a key limitation. Preventing it requires using reliable hardware, safely ejecting drives before unplugging, and verifying copies via checksums or simply opening files after transfer. This vulnerability necessitates caution, especially with critical data.