Encoding information using fewer bits than the original representation to reduce file size. Common examples include:

• .zip files, which can contain one or more files or folders that have been compressed
• .jpg files in digital photography are produced by processing complete (lossless) data from a camera’s sensor through compressing (looking for redundant/unnecessary data) into a smaller file size
• .mp3 files for audio, which compress an original audio source to reduce the file size significantly but still sound like an exact copy of the original.