Wireless Sensor Networks (WSN s) have gained prominence in technology for diverse applications, such as environmental monitoring, health care, smart agriculture, and industrial automation. Comprising small, low-power sensor nodes that sense and collect data from the environment, process it locally, and communicate wirelessly with a central sink or gateway, WSN s face challenges related to limited energy resources, communication constraints, and data processing requirements. This paper presents a comprehensive review of the current state of research in WSN s, focusing on aspects such as network architecture, communication protocols, energy management techniques, data processing and fusion, security and privacy, and applications. Existing solutions are critically analysed regarding their strengths, weaknesses, research gaps, and future directions for WSNs.