Crystal is an agile and lightweight development methodology developed by Alistair Cockburn. This methodology can be applied to small-sized teams with 6-8 developers who are working on not-so-critical applications. Crystal methodology belongs to a family of methodologies consisting of Crystal Yellow, Crystal Clear, Crystal Orange and so on. The decision on which of the flavours of Crystal to go for will depend on the size of team and the technical challenges you face. The essence of Crystal focuses on collaboration, transparency, simplicity, and continuous reflection. Therefore most teams will implement elements of crystal in a slightly different way.