With the emergence of Cloud computing, Internet of Things-enabled Human-Computer Interfaces, Generative Artificial Intelligence, and high-accurate Machine and Deep-learning recognition and predictive models, along with the Post Covid-19 proliferation of social networking, and remote communications, the Metaverse gained a lot of popularity. Metaverse has the prospective to extend the physical world using virtual and augmented reality so the users can interact seamlessly with the real and virtual worlds using avatars and holograms. It has the potential to impact people in the way they interact on social media, collaborate in their work, perform marketing and business, teach, learn, and even access personalized healthcare. Several works in the literature examine Metaverse in terms of hardware wearable devices, and virtual reality gaming applications. However, the requirements of realizing the Metaverse in realtime and at a large-scale need yet to be examined for the technology to be usable. To address this limitation, this paper presents the temporal evolution of Metaverse definitions and captures its evolving requirements. Consequently, we provide insights into Metaverse requirements. In addition to enabling technologies, we lay out architectural elements for scalable, reliable, and efficient Metaverse systems, and a classification of existing Metaverse applications along with proposing required future research directions.

翻译：随着云计算、物联网驱动的人机交互界面、生成式人工智能、高精度机器与深度学习识别预测模型的兴起，以及后新冠时代社交网络与远程通信的普及，元宇宙获得了广泛关注。元宇宙有望通过虚拟现实与增强现实技术拓展物理世界，使用户能够通过虚拟化身与全息影像在现实与虚拟世界间无缝交互。它可能影响人们在社交媒体互动、工作协作、市场营销、商业运作、教学、学习乃至个性化医疗获取等方面的行为方式。现有文献中，部分研究从可穿戴硬件设备与虚拟现实游戏应用角度探讨元宇宙，但实现大规模实时元宇宙所需的技术条件仍有待深入考察。为解决这一局限，本文梳理了元宇宙定义的时序演进过程，并捕捉其不断发展的需求特征，进而提出元宇宙需求体系。除使能技术外，我们提出了构建可扩展、可靠且高效的元宇宙系统的架构要素，对现有元宇宙应用进行了分类，并指明了未来需开展的研究方向。