How does a 75GB file become 20GB when zipped ? And then magically turn back to 75GB again ? Let’s break the illusion: - Zip files don’t delete data - They remove repetition Example If a file has: AAAAAAABBBBBBBCCCCCCC Zip stores it as: A x7, B x7, C x7 Less space. Same info. Most large files have patterns – Repeated text – Similar pixels – Duplicate metadata – Redundant code blocks Compression algorithms: – Find repetition – Store it once – Add a map to rebuild it later That map is why the file can become FULL SIZE again. Nothing is created. Nothing is lost. Just reconstructed. Why some files barely shrink ? – Videos (already compressed) – Images like JPG/PNG – Encrypted files They have less repetition that leads to less compression. - Zip isn’t Magic - Zip is actually smart math + patterns Data wasn’t reduced. It was packed efficiently.