I'm trying to understand, in very simple terms, what information might reveal a file's history. If a file is copied from one device to another, does the file itself record that it was transferred, when the transfer happened, or where it came from—such as a website, hard drive, or cloud service? What information might indicate that a document was created on the device where it is currently stored? If a file is deleted and the recycle bin is emptied, what traces might show that it used to exist, and could those traces include a date? Finally, what happens after a phone, tablet, or computer is factory-reset: is everything truly erased, or can fragments and records remain? Please explain this without assuming much technical knowledge, and include reliable sources where possible.
2 Answers
Deleting a file usually removes the operating system’s reference to it rather than immediately scrubbing every byte. On some traditional hard drives, portions of the old contents may remain in unallocated space until new data overwrites them. File-system records, thumbnails, recent-file lists, backups, application databases, and logs may also show that the file existed. A deletion time may sometimes be recorded, but it is not guaranteed and depends on the operating system and file system.
The situation is different on many modern phones and computers that use flash storage, including SSDs. Features such as TRIM, wear-leveling, encryption, and secure erasure can make deleted data difficult or impossible to recover, even if some metadata remains. Emptying a recycle bin is therefore not a universal guarantee either way.
A factory reset normally removes user accounts and makes the device appear new, but the exact result depends on the device and reset method. Modern encrypted phones often make previous data effectively unrecoverable by destroying or replacing the encryption keys. Older or less secure devices may leave recoverable remnants, and records of the reset may exist in logs, backups, or service records. A reset does not automatically preserve a reliable date proving that every deleted file was once present.
Usually, no. Copying a file does not normally add a built-in note saying “this was transferred,” when it happened, or what device it came from. The file’s normal timestamps—created, modified, and accessed—can be changed by the operating system during copying, but they are not dependable proof of a transfer. Some systems may keep extra records outside the file, such as download information, browser history, file-transfer logs, or a Windows “Mark of the Web” tag. That tag generally indicates that a file came from the internet; it does not identify the exact website or prove the complete transfer history.
What a document itself contains depends on its format. A word-processing file may contain properties such as an author name, editing application, creation date, modification date, or document revision information. These fields can be missing, manually changed, or preserved when the file is copied, so they do not necessarily prove which computer created it. The same general principles apply to phones, tablets, Windows, macOS, Linux, and other systems, although each platform stores different additional records.
So a timestamp or author field can be a clue, but it should not be treated as proof by itself. Investigators normally compare it with other records, such as system logs, backups, browser history, or cloud-service activity.
The old idea that every deleted file can simply be recovered is especially unreliable with newer phones and SSDs. Whether anything can be recovered depends heavily on storage technology, encryption, and what happened after deletion.