This document discusses object-to-object mapping and tools like AutoMapper that are used to simplify mapping between complex object models. AutoMapper uses conventions and configurations to map source objects to destination objects, ignoring properties as needed. It supports mapping through conventions based on property names, explicit configuration, projections, type conversions, and value resolvers. The document provides examples of using AutoMapper and Emit Mapper, noting that AutoMapper is more full-featured but Emit Mapper has better performance.