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data compression

A technique in computing to reduce the amount of storage space occupied by data. Methods include representing common characters by fewer bits than normal and storing frequently used words as shorter words (tokenization). Long sequences of repeated characters can be replaced by a single character and a count of how many there are, a technique called run-length encoding. By such means, text files can be reduced by up to 50% and digitized images by about 90%.

Compression techniques can be divided into two main types: lossy and non-lossy. With non-lossy compression, there is no loss in the quality of the data. With lossy compression, the compression is greater but the quality of the data is reduced; when the data is uncompressed it will be slightly different from before it was compressed. Lossy compressed is used chiefly for images, video, and music.

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