Photonic Integrated Circuits are composed of essential building blocks, including grating coupler, multimode interferometers, straight and bend waveguides, directional couplers, microring resonators, distributed Bragg reflectors, Mach-Zehnder interferometers, heaters, Phaseshifters, modulators, and photodetectors. We are providing specialized advice on PIC design, layout, fabrication, and testing to optimize performance and manufacturability with designed templates, case studies, simulation tools, and best practices in photonic circuit design.