# Metaverse Architectures: A Comprehensive Systematic Review of Definitions and Frameworks
## 3 Results
### Thematic Categorisation of Metaverse Architecture
The upper layer, typically labelled as the virtual world, virtual layer, or ecosystem, embodies the environment where user interaction, social engagement, and digital experiences occur. This triadic structure \"physical-interactive-virtual\" highlights a common architectural pattern that values system modularity and functional clarity, even though specific implementations may prioritise different disciplinary perspectives, ranging from infrastructure-centred to user-experience-focused models. The analysis of four-, five-, and six-layer metaverse architectures reveals a clear trend toward increased structural granularity and conceptual sophistication. Four-layer models, such as those proposed by [PERSON] et al. [86], [PERSON] et al. [78], and [PERSON] et al. [31], commonly emphasise bridging the physical and virtual realms through a dedicated metaverse engine layer. These models often feature both physical world and virtual world components, \begin{table}
\begin{tabular}{c|l l} \hline \hline  & **Study** & **Layer of Architecture** \\ \hline \multirow{8}{*}{**Variant**} & [PERSON] et al. [91] & Virtual World, Key Enablers Layer, Physical Layer \\ \cline{2-3}  & [PERSON] et al. [92] & Virtual Layer, Technical Layer, Physical Layer \\ \cline{2-3}  & [PERSON] et al. [68] & Virtual World, Intersection, Physical World \\ \cline{2-3}  & [PERSON] et al. [93] & Physical World, Virtual World, Enabling Technology \\ \cline{2-3}  & [PERSON] and [PERSON] [82] & Ecosystem, Interactivity, Infrastructure \\ \cline{2-3}  & [PERSON] et al. [94] & Virtual World, Intersection, Real World (Interface) \\ \cline{2-3}  & [PERSON] et al. [95] & Virtual World, Interactive World, Physical World \\ \cline{2-3}  & [PERSON] et al. [96] & Physical World, Virtual World, Technical Layer \\ \cline{2-3}  & [PERSON] et al. [48] & Ecosystem, Interaction, Infrastructure \\ \hline \multirow{8}{*}{**Variant**} & [PERSON] et al. [86] & Physical Space, Social Space, Virtual Space, Metaverse Engine \\ \cline{2-3}  & [PERSON] et al. [97] & Virtual Life, Virtual World, Metaverse Tools, Metaverse Infrastructure \\ \cline{2-3}  & [PERSON] et al. [78] & Physical World, Virtual World, Metaverse Engine, Infrastructure \\ \cline{2-3}  & [PERSON] et al. [31] & Physical World, Virtual World, Metaverse Engine, Infrastructure \\ \hline \multirow{8}{*}{**Variant**} & [PERSON] [77] & The Physical World, The Infrastructure, The Metaverse Layer, The Technology Layer, The Democratic Layer \\ \cline{2-3}  & [PERSON] et al. [5] & Digital Life, Interconnected Virtual World, Metaverse Engine, Human Society, Infrastructure \\ \hline \multirow{8}{*}{**Variant**} & [PERSON] et al. [87] & The Human World, The Physical World, The Digital World, Metaverse Engine, Intra-World Flow of Information, Inter-World Flow of Information \\ \cline{2-3}  & & \\ \hline \hline \end{tabular}
\end{table} 
Table 9: Layered-based general metaverse architecture. supplemented by layers for social space or infrastructure, reflecting an emerging socio-technical integration that balances real-world context with immersive interaction. In contrast, five-layer architectures, as introduced by [PERSON] [77] and [PERSON] et al. [5], exhibit greater abstraction by incorporating higher-order layers like the democratic layer and human society, indicating a shift toward governance mechanisms and user-centric societal modelling. The five-layer models also reveal distributed responsibilities across technical, virtual, and socio-political domains, suggesting an evolution from system orchestration to platform accountability and interoperability. Extending this progression, the six-layer model proposed by [PERSON] et al. [57] introduces Intra-World and Inter-World Flow of Information layers, formalising cross-environment communication and systemic data exchange. This structure exemplifies a highly modular and scalable framework capable of supporting diverse, interconnected metaverse subsystems.