A unit may be defined as an independent material element of meaning, one that interacts with other units in order to create greater meaning. They may be objects (person, insect, shoes) or material manifestations of concepts, emotions, or literary motifs (jealousy, racial tension, order, search for meaning). Aggregates of these units form systems , and may interact as a unified whole (system operations ) or individuallly (unit operations). This term is coined by Ian Bogost in the first chapter of Unit Operations: An Approach to Videogame Criticism (5).