Lossy is a term that is commonly used when referring to compression methods. A lossy form of compression means that after data is compressed it can no longer be uncompressed with the original information. This is different than a lossless form of compression. An important thing to remember about lossy compression is that once data compressed by a lossy method, you can never get it back.

Lossy compression works well for information that will be observed in an analog method such as visual or auditorial. Music, images, and movies are good examples.

Common forms of lossy compression include fractal and wavelet.