This chapter defines the semantics, and clarifies the terms and notions addressed in the book. Researchers have very often explained the complexity of virtual teams in comparison with conventional teams. They approach virtuality through its level of dispersion that is spatial, organizational, social and/or functional, and, then, focus on the differences in comparison with face-to-face interactions. The variable degree of virtuality is considered too. The result of the research enables a gradual approach to a deeper structured appreciation of the attributes, boundaries and processes of virtual teams, including the involved critical factors.