Description Logics are knowledge representation languages that have been studied extensively in artificial intelligence over the last two decades. This Handbook covers all aspects of research in this field including theory, implementation, and applications. Its appeal is broad, ranging from more theoretically-oriented readers, to those with more practically-oriented interests who need a sound and modern understanding of knowledge representation systems based on Description Logics. The chapters by some of the most prominent researchers in the field first introduce the basic technical material before addressing the current state of the subject. This unique reference can also be used for self-study or in conjunction with knowledge representation and artificial intelligence courses.