File Extension GZ
File extension GZ is associated with a file compressed using the gzip (GNU File extension Zip) utility. Gzip was first released in 1992, and was developed as a replacement for compress under UNIX, offering significantly better compression ratios and avoiding patented algorithms. GZ files are most commonly found in UNIX-based environments, though tools to create and decompress GZ files are also readily available for other platforms.
GZ files are similar to File extension BZ2 files in that they are usually compressed archives, and are typically used for backup purposes or packaging files for transfer over a network to reduce the bandwidth required. Whereas applications which perform similar functions on Windows and Mac usually perform both archiving and compression, utilities in UNIX-based operating systems typically only serve a single purpose. Gzip is no different, and is usually used in conjunction with an archiving utility such as tar which will be used to create a single archive file from a specified file and folder structure. Then, the file can be compressed using gzip, and the resultant file will have a TAR.GZ file extension which denotes a compressed archive.
As GZ files are compressed, it is not possible to tell the contents without opening the file. If a file has a TAR.GZ extension then decompressing the file will result in an archive, and if it simply has a GZ extension then the contents will be a single file. It is possible that GZ files contain malicious software, particularly as they are often used to package applications and files for distribution over the Internet, so should be checked with an anti virus application before opening, particularly if the source of the file is unknown.
GZ files can be opened on UNIX-based systems from a shell prompt with gunzip, which is part of the gzip utility. Alternatively, GZ files can be opened on Windows systems using most popular archiving and compression applications such as WinZip, WinRAR, WinAce or 7-Zip, or Smith Micro StuffIt Expander, the latter of which is also available on Mac.