The Crystal family of agile process models was developed by Alistair Cockburn in the 1990s. Cockburn classifies the process models of the Crystal family according to color and criticality. The color corresponds to the team size—the darker the color, the larger the team. The criticality corresponds to the severity of the damage that faulty software can cause. This classification makes sense because, on the one hand, larger projects entail increased communication effort, and on the other hand, higher criticality requires more effort in quality assurance. Nevertheless, the focus of the approach is not on a specific, defined procedure within the project. Instead, general principles are postulated and project properties to be achieved are defined.