What is a "detail" in architecture? The concept of detail has long played an important role in the discourse and practice of architects, but the meaning of the term has been understood in radically different ways, from construction detail to ornament. Detailing Worlds is the first book to examine how the complex and manifold meanings of our contemporary understanding of architectural detail came to be. It tells the story of the evolution of an architectural concept from the term's origins in the 18th century to the present day, examining five different "worlds" of practice - the academic, technician, student, engineer, and architect - to show how each of these different contexts conditioned the emergence of new understandings of detail. Detailing Worlds will appeal to historians of architectural practice and to designers too, for its insights on contemporary modes of thinking and speaking about the practice of building design today.