Robots that are used to support humans in dangerous environments, e.g., in manufacture facilities are established for decades. Now, a new generation of service robots is focus of current research and about to be introduced. These intelligent service robots are intended to support humans in everyday life. Thus, it is imperative for the acceptance of such robots to provide interaction interfaces that we humans are accustomed to in comparison to human-human communication. Consequently, intuitive modalities like gestures or spontaneous speech are needed to teach the robot previously unknown objects and locations. Then, the robot can be entrusted with tasks like, fetch-and-carry orders even without an extensive training of the user. In this context, this work introduces the multimodal Object Attention System which offers a flexible integration of common interaction modalities in combination with state-of-the-art image and speech processing techniques from other research projects. This book targets researchers, students, and interested audience in the field of cognitive robotics.