The term AD ADD-ON can be broken down into two parts: HOC (3 letters) and LIB (3 letters). HOC stands for 'Head of Content' and is a role in the media industry that involves overseeing the content creation process. LIB stands for 'LIBRARY' and is a collection of digital assets, such as images, videos, and audio files, that are used to create content. Together, the term AD ADD-ON refers to a LIBRARY of digital assets that are used to create advertisements.