7z

7z refers to both the 7z archive format and the software 7-Zip. Created by Igor Pavlov, the format was introduced in 1999 and has since become a widely used open archive format. The primary implementation, 7-Zip, is free and open‑source software for creating and extracting archives. The 7z format stores data in a single archive and typically uses the LZMA family of compression methods, notably LZMA and LZMA2, with optional AES-256 encryption. Archives can be split into multiple volumes and may include password protection.

Key advantages of 7z include high compression ratios, especially for large collections of files, and solid compression, which compresses related data as a single block to improve results. The format supports multiple compression codecs, encryption, and self-extracting executables on Windows. It also preserves file metadata and supports large file and archive sizes.

The 7-Zip program provides both a graphical user interface and a command-line interface. While primarily developed for Windows, ports and compatible tools such as p7zip exist for Linux and macOS, enabling creation and extraction of 7z archives on those platforms. The format is widely supported by other archivers and operating systems, though not always by default in the system file manager.