Data compression

In computer science and information theory, data compression, source coding, or bit-rate reduction involves encoding information using fewer bits than the original representation.

Advantages of File Compression

• Storage space - Smaller files mean less space for storage and now files can be compressed up to 1/100th of the original
• Electricity - Every peny that you spend on storage, you need to spend another dollar on cooling, therefore if you save on storage, you save on cooling
• Viewing - Files no longer need to be downloaded in their entirety before viewing because they are now able to open while they are being downloaded
• Printing - Files can now be printed 10-100 times faster
• Transmission time - Uploading and downloading will no longer be an issue since uploading and downloading takes only 1/10th of the time it would normally take

If you download many programs and files off the Internet, you've probably encountered ZIP files before. This compression system is a very handy invention, especially for Web users, because it lets you reduce the overall number of bits and bytes in a file so it can be transmitted faster over slower Internet connections, or take up less space on a disk. Once you download the file, your computer uses a program such as WinZip or Stuffit to expand the file back to its original size. If everything works correctly, the expanded file is identical to the original file before it was compressed.

At first glance, this seems very mysterious. How can you reduce the number of bits and bytes and then add those exact bits and bytes back later? As it turns out, the basic idea behind the process is fairly straightforward. In this article, we'll examine this simple method as we take a very small file through the basic process of compression.

Most types of computer files are fairly redundant -- they have the same information listed over and over again. File-compression programs simply get rid of the redundancy. Instead of listing a piece of information over and over again, a file-compression program lists that information once and then refers back to it whenever it appears in the original program.