Wireless sensor networks (WSNs) have found widespread application in diverse domains, leading to a wide range of requirements and characteristics. This paper explores the design space of WSNs by analyzing various dimensions that define their design. The authors argue that existing applications occupy different points in this design space, highlighting the need for a structured approach to discuss and coordinate research in WSNs. The design space of WSNs is characterized by several key dimensions, including deployment, mobility, cost, size, resources, heterogeneity, communication modality, infrastructure, network topology, coverage, connectivity, network size, lifetime, and other quality-of-service (QoS) requirements. Each dimension influences the design and implementation of WSNs, and understanding these dimensions helps in developing flexible software frameworks that can adapt to different application needs. The paper discusses various applications that illustrate the diversity of WSNs. These include bird observation, zebra monitoring, glacier monitoring, cattle herding, bathymetry, ocean water monitoring, grape monitoring, cold chain management, avalanche rescue, vital sign monitoring, power monitoring, parts assembly, military vehicle tracking, self-healing mine fields, and sniper localization. Each application demonstrates different aspects of the design space, such as varying levels of mobility, heterogeneity, communication modality, and network topology. The authors conclude that a single hardware platform is unlikely to support all possible applications, and a modular approach with different platforms covering the design space is necessary. For software, the complexity of the design space poses challenges, and appropriate abstractions and middleware concepts are needed to simplify development. However, some design space dimensions are difficult to hide from developers, and exposing application characteristics to the system is crucial for energy and resource efficiency. The paper suggests that a modular software architecture with dynamic extension of appropriate modules could help in achieving efficient and flexible WSNs. Overall, the design space approach provides a framework for discussing and coordinating research in WSNs, and it brings clarity to discussions about the typical characteristics and requirements of WSNs.Wireless sensor networks (WSNs) have found widespread application in diverse domains, leading to a wide range of requirements and characteristics. This paper explores the design space of WSNs by analyzing various dimensions that define their design. The authors argue that existing applications occupy different points in this design space, highlighting the need for a structured approach to discuss and coordinate research in WSNs. The design space of WSNs is characterized by several key dimensions, including deployment, mobility, cost, size, resources, heterogeneity, communication modality, infrastructure, network topology, coverage, connectivity, network size, lifetime, and other quality-of-service (QoS) requirements. Each dimension influences the design and implementation of WSNs, and understanding these dimensions helps in developing flexible software frameworks that can adapt to different application needs. The paper discusses various applications that illustrate the diversity of WSNs. These include bird observation, zebra monitoring, glacier monitoring, cattle herding, bathymetry, ocean water monitoring, grape monitoring, cold chain management, avalanche rescue, vital sign monitoring, power monitoring, parts assembly, military vehicle tracking, self-healing mine fields, and sniper localization. Each application demonstrates different aspects of the design space, such as varying levels of mobility, heterogeneity, communication modality, and network topology. The authors conclude that a single hardware platform is unlikely to support all possible applications, and a modular approach with different platforms covering the design space is necessary. For software, the complexity of the design space poses challenges, and appropriate abstractions and middleware concepts are needed to simplify development. However, some design space dimensions are difficult to hide from developers, and exposing application characteristics to the system is crucial for energy and resource efficiency. The paper suggests that a modular software architecture with dynamic extension of appropriate modules could help in achieving efficient and flexible WSNs. Overall, the design space approach provides a framework for discussing and coordinating research in WSNs, and it brings clarity to discussions about the typical characteristics and requirements of WSNs.