Global manufacturing with mass customization and ever shorter product life cycles have led to the requirement for rapidly reconfigurable manufacturing systems. Advancements in Information Communications Technologies (ICT) have facilitated rapid reconfiguration, not only at the hardware level but also at the software level. Nonetheless, additional efforts are still required to achieve the objective of autonomous reconfiguration. The formal representation of knowledge for autonomous processing has emerged as a main topic in achieving autonomy of reconfiguration processes. This book targets the topic of knowledge representation and reasoning machines and introduces the concept of domain ontologies. Domain ontologies are the formal representation of knowledge about manufacturing systems, industrial equipment, industrial processes, and products to be manufactured. The use of domain ontologies has received increasing attention within the manufacturing field, most notably since the emergence of Web-based solutions and the Semantic Web. This handy reference presents a methodology for building domain ontologies, introduces tools for editing them, and discusses logic reasoners, which are used to process the ontologies autonomously.