Data compression is the process of encoding, restructuring or otherwise modifying data in order to reduce its size. Fundamentally, it involves re-encoding information using fewer bits than the original representation.
For data transmission, compression can be run on the content or on the entire transmission. When information is sent or received via the internet, larger files, either on their own or with others, or as part of an archive file, may be transmitted in one of many compressed formats, like ZIP, RAR, 7z, or MP3.