ZIP
An archive format, published by PKWARE in 1989, that bundles several files into one and compresses them.
ZIP is an archive format that bundles several files and folders into a single file and compresses them for transfer. PKWARE published the APPNOTE specification in 1989; as of October 2026 the edition is 6.3.10, dated 1 November 2022. The file extension is .zip.
Each file is compressed separately, and a central directory at the end lists the whole contents. The standard method is Deflate (method 8), a form of lossless compression, so the original data comes back exactly. Photos that are already compressed, such as JPEG, shrink only a little.
- Encryption: APPNOTE itself describes the traditional encryption (commonly called ZipCrypto) as weak; there is also an AES method with 128-bit or 256-bit keys
- File names: when general purpose bit 11 is set, names are stored in UTF-8. When it is not, the specification says CP437, but many archives hold names in the encoding of the system that made them (cp932 on Japanese Windows), which is where garbled names come from
- Where it opens: Windows, macOS, the Files app on iPhone and Files by Google on Android can extract it with no extra software
The steps for opening a password-protected ZIP on a phone are in How to Open a Password-Protected ZIP on a Phone.