Lossless compression is a data compression method that does not lose any information during compression or decompression. It makes files smaller by removing redundancies. For example, if data in a file had "xxxxxxxxxx," it could be written as "10x" to save space. The process is lossless because none of the essential data is gone, just written differently.
What is lossless compression used for?
Lossless compression is commonly used on executables or certain image files including GIF and PNG. Lossless compression is used on these files as they require all of their original data function correctly.
Some music sharing services, such as iTunes, offer a lossless compression format for its downloads. The file size of each song is much larger than an MP3, but the audio quality will be close to perfect.