Definition:
The term lossy is used to describe a compression algorithm that produces a file that is not identical to the original. For example, when an MP3 file is created by ripping a CD track, it will have lost some of the detail of the original recording. This is due to how the MP3 compression algorithm works. A lossy format can apply to any type of format and not just audio; image files in the JPG format for example are also lossy.
