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、物联网赋能的人机交互界面、生成式人工智能、高精度机器与深度学习识别及预测模型的涌现，以及后疫情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和增强现实技术扩展物理世界，使用户能够通过虚拟分身和全息投影与真实及虚拟世界无缝交互。它可能深刻影响人们在社交媒体互动、工作协作、营销与商业、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，多项研究从硬件可穿戴设备与虚拟现实游戏应用角度审视元宇宙，但实现实时、大规模可用的元宇宙所需技术条件仍有待深入探究。为解决此局限，本文梳理了元宇宙定义的时间演变脉络，提炼其不断演进的需求特性，进而阐释元宇宙的核心需求。在解析使能技术的基础上，我们提出了面向可扩展、可靠、高效元宇宙系统的架构要素，建立了现有元宇宙应用的分类体系，并提出了亟待开展的未来研究方向。