Data Backup Digest

File Compression is the process of taking data and making it smaller. This is often done by removing redundant information and/or using some type of encoding scheme. File compression is usually used for files served over the Internet since they need to be as small as possible to reduce download times. As more applications and software are distributed over only the Internet, instead of on CDs or DVDs, file compression will definitely be needed to reduce the size of installation files. File compression is often combined with archiving, but they are slightly different things. Compression reduces the size of the file, whereas archiving combines multiple files into one file with no reduction in the total size. Most compression tools can do both, so I won’t treat them as two completely different things. Also, many compression formats both compress and archive. For instance, Gzip (.gz) compresses files and Tar (.tar) archives files, so a common compression format, especially on Linux and for open-source software, is tar.gz. This compression format combines both Tar and Gzip for compression and archiving. There are hundreds of compression schemes and formats out there, but I’m going to run down some of the best file compression standards and tools.

Perhaps the most well known file compression format, especially for use on the internet, is Zip. Mac and Windows have tools built-in to the operating system to compress data to a Zip file and to decompress a Zip file. It is a relatively fast compression format and has become the most popular compression format for most people. If you need some extra options, like multiple types of encryption or the ability to password protect files, use WinZip. WinZip is the most popular and well-know commercial software for zipping files. It costs $29.95 and has a trial version. In tests, WinZip preforms faster than the built-in compression tool from Microsoft.

7z is a file compression format that is gaining popularity for how small it can compress files. The main downside to it compared to Zip is that it is usually slower. The most popular tool for compression to 7z is 7-Zip, which is a free and open-source software application for Windows. Another file compression scheme that can produce small files is RAR. 7z often times can produce slightly smaller files, but RAR is usually better for certain types of files like MP3s. For Windows, the most popular software to make RAR files is WinRAR. It is shareware, so it’s free to download, but there are paid options for certain features. The same company also has command line programs for Mac.

As I alluded to before, Tar.gz is very popular for software packages distributed for Linux-based operating systems. Another similar format often used in on Linux is Tar.bzip2. Linux includes command line utilities to compress files into both formats.

The main tradeoff you have to deal with between compression formats is speed and size. In most cases, the longer it takes to compress a file, the smaller it will be. Zip is perhaps the fastest and in most cases RAR is faster 7z, but 7z usually compresses to the smallest file size.