Explore the physics of functional networks in this comprehensive lecture from the Workshop on Topology: Identifying Order in Complex Systems. Delve into optimal network topology, sound control in mechanical networks, and physical response optimization. Investigate the growth and remodeling of vascular networks, minimizing dissipation through growth, and optimal trade-offs in plant leaves. Examine structural networks in biology, focusing on leaf venation, and learn about making networks rigid through constrained optimization and simulated annealing. Discover the design principles for resilient grids, optimal noise-canceling networks, and the connection between engineering and biology. Analyze AC power grids as coupled phase oscillators and explore the formation and prediction of loops in network structures. Compare topological findings to real leaf networks and gain insights into the complex world of functional network physics.