This book outlines a range of user experiments, providing comprehensive evaluations that underline the rationale behind implementing collaborative 3D virtual offices in corporate settings and 3D classrooms in educational institutions. In this book, radically new scientific approaches are taken for studying user effectiveness in the realm of 3D graphical interfaces. The emergence of VR is seen in the book as a pivotal moment in the evolution of information technology, marking a shift from the era of DOS and Windows to immersive digital spaces. Through extensive research and experimentation, it is convincingly demonstrated that integrating 2D user interfaces, such as windows, images, and 2D widgets, into 3D digital environments significantly enhances user effectiveness in terms of online collaboration, memory, recall, and comprehension of complex workflows. Moreover, valuable advice and design principles are offered to guide the creation of such working 3D digital environments.