Sensor fusion is the process of combining data from multiple sensors to obtain a more accurate, reliable, or comprehensive understanding of an environment or phenomenon than could be achieved by using individual sensors alone. As a research field and methodological approach, it investigates algorithms and techniques for integrating information from diverse sensing modalities, addressing challenges such as data alignment, uncertainty management, and the exploitation of data redundancy and complementarity. Its significance lies in enhancing the robustness, accuracy, and completeness of perception and state estimation in complex systems, enabling improved decision-making and performance across various domains.