Compression

Mathematicians have found ways to reduce the space required to store certain types of data. Compressed data uses less disk space, and can be transmitted or copied more quickly.

 

Depending on the type of data, compression can reduce the size of the data by as much as 90%. Reductions of 50% are more common. And some data cannot be compressed at all.

 

Compressed data appears to be garbled, since its contents have been rearranged. Before compressed data can be used, it must first be decompressed, or restored to its original state and size.  Windows performs the required decompression automatically, for files and folders it compressed. Data compressed using other software, for example WinZIP, must be decompressed by the same program before use.