.gz File — Gzip Compressed File

GZ files use gzip compression, a free compression algorithm and file format based on the DEFLATE algorithm (combining LZ77 and Huffman coding). Created by Jean-loup Gailly and Mark Adler in 1992 as a patent-free replacement for the Unix compress utility, gzip has become one of the most widely used compression formats in computing. Gzip compresses single files (unlike ZIP which is an archive format) — to compress multiple files, gzip is combined with tar to create .tar.gz (or .tgz) archives. Gzip is the standard compression method for HTTP content encoding, used by web servers worldwide to compress HTML, CSS, JavaScript, and API responses before transmission, typically reducing transfer sizes by 60-80%. The format includes CRC-32 checksums for data integrity verification and original file size metadata. Gzip provides a good balance of compression ratio and speed, making it practical for both real-time compression (web serving) and archival uses. The format is natively supported by all Unix-like operating systems and most modern tools. Zlib, the core compression library behind gzip, is used in PNG, ZIP, PDF, and countless other formats.