Introduced by Alistair Cockburn, Crystal Methods, which is a collection of Agile software development approaches, focuses primarily on people and the interaction among them while they work on a software development project. There is also a focus on business-criticality and business-priority of the system under development. Unlike traditional development methods, Crystal doesn’t fix the tools and techniques of development, but keeps people and processes at the core of the development process. However, it is not only the people or the processes that are important, rather the interaction between the two that is most important.
“Crystal is a family of human-powered, adaptive, ultra light, ‘stretch-to-fit’ software development methodologies.” (Alistair Cockburn; http://alistair.cockburn.us/Crystal+methodologies.)