This document provides an overview and introduction to the Level of Development (LOD) Specification guide. It describes the LOD Specification as a reference tool to improve communication about the characteristics of building elements in BIM models at different stages of development. The summary outlines the background and intent of the LOD framework, how it expands on the AIA's LOD definitions, how the specification should be used and organized, and provides a high-level executive summary of the contents and purpose of the LOD Specification guide.