This paper presents a layered architectural framework for context-aware systems, which are designed to gather and adapt to context data to enhance usability and effectiveness. The authors introduce various existing context-aware systems, focusing on middleware and frameworks that facilitate the development of context-aware applications. They discuss different approaches and analyze key aspects of context-aware computing based on the presented systems. The paper covers the history of context-aware systems, the classification of context instances, and the design principles for context-aware systems, including architecture, context models, and sensing mechanisms. It also compares existing systems and frameworks, highlighting their similarities and differences in terms of layered structures, context data acquisition, and processing. The paper concludes by discussing historical context data, security, and privacy issues, emphasizing the need for standardized formats and protocols to enhance the development of context-aware systems.This paper presents a layered architectural framework for context-aware systems, which are designed to gather and adapt to context data to enhance usability and effectiveness. The authors introduce various existing context-aware systems, focusing on middleware and frameworks that facilitate the development of context-aware applications. They discuss different approaches and analyze key aspects of context-aware computing based on the presented systems. The paper covers the history of context-aware systems, the classification of context instances, and the design principles for context-aware systems, including architecture, context models, and sensing mechanisms. It also compares existing systems and frameworks, highlighting their similarities and differences in terms of layered structures, context data acquisition, and processing. The paper concludes by discussing historical context data, security, and privacy issues, emphasizing the need for standardized formats and protocols to enhance the development of context-aware systems.