The motherboard in a Samsung Galaxy S8 is the main internal circuit board that acts like the phone’s “brain and nervous system.” It holds and connects all the critical parts that make the phone work, including the processor (CPU), memory (RAM and storage), graphics chip, wireless radios (for 4G, Wi-Fi, Bluetooth), power management, camera control, and other key electronics. The motherboard ensures all these components communicate and work together so your phone can power on, run apps, take pictures, connect to networks, and perform daily tasks.