We live in an information age.  Blah Blah Blah



	There are two types of compression, lossy and lossless.  With lossy

compression, the data after decompression is not identical to the original,

but it "resembles" it.  Lossy compression requires some knowledge of the

data, to insure that the distortion is not noticeable.  It almost always

produces a smaller compressed file than lossless compression since the

data can be manipulated slightly to fit a stricter mathematical model.

Lossy compression is most commonly used on data that will be interpreted

by a human, rather than a computer, such as audio (such as MPEG-III and

OggVorbis), video (such as MPEG-I and MPEG-IV), and images (such as JPEG-LS.) 

Lossless data compression reduces the size of data without distorting the

original data.  It is divided into at least two types, variable size and 

variable success.  Variable size compression compresses to an unknown size

(which may be larger than the original), and can always be returned to the

original.  Variable success compression will either compress data to a size

at a constant proportion to the original (the proportion to the original is 

called the "compression ratio"), or fail to compress.  Lossless compression

is used for any data that needs to be reduced in size but not distorted.



	An algorithm is "step-by-step procedure for solving a 

problem or accomplishing some end especially by a computer" (Merriam 2000).

Therefore, a "compression algorithm" is roughly the steps involved in

compressing data.  Most compression programs implement only one compression

algorithm and this algorithm is applied over an entire set of data (such as

a file.