Path planning is a complex problem, which involves meeting the physical constraints of the unmanned aerial vehicles (UAVs), constraints from the operating environment and other operational requirements. The foremost constraint to be met is that the paths must be flyable. Flyable paths are those that meet the kinematic constraints of the UAV. Satisfying this constraint ensures that the motion of the UAV stays within the maximum bounds on manoeuvre curvature. The safety of the path is measured by the ability of the path to avoid threats, obstacles and other UAVs. The path must maintain collision avoidance with other friendly UAVs and also must be flexible enough to avoid environmental obstacles and threats. Also, additional constraints – such as generating shortest paths, and minimum fuel and energy consumption paths – can be included for better performance and efficiency of the mission. This book has grown out of the research work of the authors in the area of path planning, collision avoidance and path following for single and multiple unmanned vehicles in the past ten years. The algorithms described here result in the planning of paths that are not only flyable and safe but also implementable for real-time applications