What is GZ file extension (Gzip compressed format) (original) (raw)

What are GZ files, GNUZip Deflate compression algorithm

GZ file extension

GZ extension designates a single file compression format, created for GZip (GNU Zip or "gratis Zip") project, started in 1992 by Jean-Loup Gailly and Mark Adler in order to provide a free replacement for proprietary / commercial data compression solutions.
Compression is based on DEFLATE algorithm (also used as default algorithm in PKZip/WinZip's .ZIP format), a combination of Lempel-Ziv coding (LZ77) and Huffman coding.

GZ file format specs

Deflate is obiquitously employed as fast (and light in resources) compression algorithm (as in zlib / PNG lossless compression and Zopfli project), and recently is being surpassed in speed by new actively developed projects as Google's Brotli and Facebook's Zstandardproviding either superior compression ratio at high compression levels, and faster, near real time compression and extraction speed at whith lower settings, while retaining a comparable compression ratio to Deflate.

Support for GZip file format

7-Zip (and PeaZip, which handles zip and gzip files through Open Source 7-Zip / p7Zip binary backend) use an custom optimized DEFLATE implementation producing better compression ratios than standard reference DEFLATE implementation, keeping full compatibility with other compression utilities working on .gzip files, but using more processor time (gzip compression and extraction is however very fast, and CPU/RAM-light, for today's machines capabilities).

PeaZip has full support for GZip standard, including compression, listing, testing, and extraction. Read also: how to create and open GZ files

What is TAR.GZ file type

Gzip's GZ file format lacks file archiving feature - it can compress each single file, but cannot consolidate multiple input file in a single (compressed) container archive - for that reason it is commonly used on Unix/Linux world to compress TAR archives(as well as Brotli .BR, BZip2 .BZ2, LZMA .XZ, Zstandard .ZST...) - archiving format which can consolidate multiple files in a single package and preserve filesystem information (file attributes, date/time etc), but lacks compression capabilities - producing TGZ file (if single file extension convention is used), alternatively identified by TAR.GZ extension if multiple file extension convention is used.

Read more about .gz extension: GZipcompression program and GZ file type page on Wikipedia, and on GnuZip domain.

Synopsis: What is gz file format extension. What are TGZ and TAR.GZ file types. Gzip compression (Deflate algorithm) compared to Brotli, Zstandard for speed and compression ratio. GNUZip compressed files features and specifications.

Topics: GZ file extension

PeaZip > FAQ > What is GZ file extension (Gzip compressed format)