What’s Data Compression?

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Data compression reduces file size, making them faster to transfer and leaving more storage space. Compression involves applying an algorithm that makes repetitive bits redundant. Files may be split into pieces before sending, and various music formats use compression techniques. Compression programs are widely available online.

Data compression is an umbrella term for a group of technologies that encode large files to reduce their size. Smaller files take up less space, leaving you with more storage space. They’re also faster to transfer over a network, whether it’s the Internet, an intranet, or a local area network (LAN).

In the 1970s, various techniques were available for archiving files or putting them together in one package to avoid sending multiple files between computers. The idea was soon expanded upon with data compression techniques, so the term “archive” is now often used to describe a compressed file.

Data compression involves applying an algorithm that makes some of the repetitive bits redundant. It’s sort of like a shorthand map that is stored with the compressed file. Once uncompressed, the map restores all missing bits, reconstituting the complete file. This technique can be used with text, graphics, executable programs, and multimedia files, although some file types compress better than others.

The data compression technique most commonly recognized today was originally used in the DOS operating system before Microsoft Windows became ubiquitous in the mid-1990s. Author Phil Katz eventually called these compressed files compressed files: the idea was that when the files were decompressed (uncompressed), the entire contents “came out”. Files used with this method have the extension .zip.

Files that are extremely large even when compressed may be split into pieces before being sent over the network. The pieces are picked up and reassembled at the receiving end. The main compression technique for large files, even since the days of DOS, is called RAR, named after the author Eugene Roshal. Programs that support Roshal ARchive files can create a RAR set from a large media file, for example, or decompress an existing RAR to reassemble a movie or program. These files have the extension .rar or, for multipart files, part01.rar, part02.rar or .r01 r02.

Various music formats also use other data compression techniques to shrink the files while keeping the original quality as much as possible. The most obvious example is the .mp3 format. In this case, however, the compressed file is not an archive and cannot be decompressed. The bits that are removed to get the smallest file size are gone forever. Other techniques used for music files retain higher quality but are also larger in size.
Data compression programs are widely available online. A compressed or RAR file requires a program that supports that method to decompress or decompress it. Most programs support multiple types of compressed files, and many of these programs are freeware.




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