This literature review offers an in-depth overview of recent advances in routing optimization for Unmanned Aerial Vehicles (UAVs), a field central to improving the performance, reliability, and flexibility of UAV systems. The review is organized into five categories: (1) multi-objective mission planning, (2) algorithmic design and optimization techniques, (3) energy efficiency and resource allocation, (4) communication protocols and network management, and (5) context-specific applications and environmental adaptability. The review highlights methodological progress and algorithmic approaches developed to balance competing demands such as mission effectiveness, energy use, and communication... More >