The aim of this book is to educate the readers regarding expert systems. Intelligent systems aka expert systems fulfill the purpose of their name in the way that they act as facilitators in this procedure. These are systems that are based on specialist information on any topic in order to emulate human capability in the exact field. To attain this information, the knowledge experts, also called software engineers, require expanding of methodologies for intelligent systems. In this field there is still no unified methodology that supplies efficient techniques and tools to facilitate any new advancement.