The architecture description language (ADL) is the foundation of software development based on software architecture. An ADL supporting stepwise refinement can make it more convenient that a good design leads to a good implementation. The architecture description language XYZ/ADL can support the stepwise transition from higher-level architectures to lower-level architectures, because it is based on the temporal logic language (TLL) XYZ/E, which can represent both dynamic semantics and static semantics under a unified logical framework. In this paper, the framework and syntax of XYZ/ADL is presented and its underlying semantics is explained using XYZ/E, and how to describe software architecture and software architecture style using XYZ/ADL is introduced.