The .zip file extension is the most well known file type related to compressed and archived files. First released in 1989, the format is still widely used and is built into Microsoft Windows releases since 1998. It is also supported by Apple's OSX operating system. The ZIP format supports compression via several different techniques and even supports simply archiving of files without compression. Despite being 20 years old, the ZIP format looks set to continue to thrive whilst bandwidth and storage remain relatively costly.
The compression techniques used to create a .zip file do so by compressing each file individually. This has the advantage of potentially using different appropriate compression techniques for each file within the archive, however under normal circumstances it limits the potential compression capability. Although the ZIP format allows for up to 10 different types of compression to be chosen, the DEFLATE method is the most common. DEFLATE is based on Huffman coding.
A .tar.gzh file extension represents a collection of files grouped together as a Tape Archive File (TAR) that has been compressed using the Gzip compression application. This means that the file is given a double extension relating to both the archiving method and the compression method. Files of this nature are often referred to as a tarball.
A file with the .tar.gz extension will be using gzip compression. This is achieved by identifying and temporarily replacing similar bits of data within the file, which reduces the overall size of the file. This method of compression is well established for use with TAR files and is now increasingly common for sending and receiving web page data.