Compression is one of those wonderful things we have grown accustomed to in the computer world. You wave a magic wand and —poof!— a file suddenly shrinks to a fraction of its size! You wave the wand again and —pop!— the original file is restored down to the last bit. How can this possibly work? Let’s find out! Compression 101 At a high level, compression is about rewriting data so that it conveys the same information in fewer bytes.