The Three Layers of Rot
While "Disc Rot" is physical and "Bit Rot" is magnetic, "Data Rot" is often existential. It is the gradual loss of the ability to interpret the signal.
1. Physical Layer (The Medium)
The CD scratches, the hard drive clicks, the tape snaps. This is the hardware failing.
2. Logical Layer (The Code)
The file allocation table (FAT) corrupts, and while the file is still on the disk, the OS can no longer find its address.
3. Semantic Layer (The Meaning)
The file opens, but it is a "Excel 95" spreadsheet that modern Excel renders as gibberish symbols. The data is fundamentally "rotten" because the interpreter is dead.
Field Notes
The NASA Tapes: In the 2000s, NASA admitted it had lost the original high-quality footage of the Apollo 11 moon landing. The data didn't "rot" physically; it was simply recorded over or misplaced in a massive, poorly indexed archive. This is "Administrative Data Rot"—decay caused by human negligence.
The "Vint Cerf" Warning: One of the fathers of the internet famously warned of a "Digital Dark Age" where we have petabytes of data but no software to read it. He advocates for "Digital Vellum"—preserving the software and the OS alongside the file.