Human-Computer Integration (HInt) is an emerging paradigm in the human-computer interaction (HCI) field. Its goal is to integrate the human body and the computational machine. Because HInt is not an isolated area of research, the authors draw upon discussions from related perspectives, including cybernetics, augmentation, cyborgs, and wearables. While these prior works provide a basis for HInt, and some of their associated challenges also apply to HInt, the authors focus on articulating the HInt challenges that are of particular relevance to HCI. The monograph makes three contributions: First, the authors apply two key dimensions from psychology - bodily agency and bodily ownership - to enhance our understanding of HInt systems. Second, they use these two dimensions to provide new perspectives on user integration experiences and to develop an integration systems design space. Third, they use the design space and its two dimensions to articulate HInt's key challenges and group these challenges into four areas: design, society, identity, and technology. Ultimately, the work aims to facilitate a more structured investigation into human body and computational machine integration.