What are design systems? The definition can understandably vary from one person to the next, or one speciality to the next. My definition is quite simply the holistic, yet modular, creation and maintenance of user interfaces. By modular I mean opinionated and transportable units or concepts that can be re-used in different contexts. Even when adapted, these manifest units or concepts always inherit from a centralised library of design decisions, which results in a more reliable delegation of design opinions into the context in which they are used.