Compression

=**Compression!!**= Compression is the process of encoding information using fewer bits than the original representation would use. In the other word, it's called as source coding or bit-rate reduction.
 * Definition**

-Mainly to get free spaces in the hard disk**.** -To save the time when the file is required to be sent to somewhere else.
 * Why do we need it?**

Lossy image compression is used in digital cameras, to increase storage capacities with minimal degradation of picture quality. In lossy's case, it can save larger spaces (compress a lot), but the quality gets low. E.g. MPEG-2 Video codec**.** The best modern lossless compressors use probabilistic models (here probabilistic means randomized algorithm, such as prediction by partial matching). In lossless's case, It can keep the quality of the file, but it doesn't compress a lot. E.g. Zip method.
 * Two types of Compression**
 * Lossy**
 * Lossless**

E.g. AVI to mp4 or audacity files to mp3.
 * Encoding??**
 * Encoding** is a similar to the compression but it can expand the size of file (not only compress the file) and change the format of the file.

To do compression, it requires certain software to compress the files. Moreover, it needs the software again to open or to expand it.
 * The problem of the compression**

Useful Compression software AlZip for the windows - Sometimes when you have a huge file, such as 8GB Movie, the AlZip spreads up the files into several files in AlZip format so it is easy to send though USB or Internet. The Unarchiver for the Mac - it allows most of zip files to unzip and it deletes zip files when you unzip the zip file.

[|BridgeSTOR Makes Available Free Data Reduction Simulator] The Virtual Storage-Advanced Data Reduction Simulator tool enables storage managers to predict the effects of deduplication and compression on their primary storage capacity requirements.
 * News article related to Compression**

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