SoC, stands for system-on-a-chip is an integrated circuit that incorporates a majority of components (chipset features) present on a computer into a single silicon chip.
Along with a processor, the SoC usually contains a GPU (graphics processor), memory, USB controller, power management circuits, and wireless radios. Having all of these components on a single chip means SoCs use less power, provide a better performance, require less space and are more reliable than multi-chip systems.
Most SoCs today come inside mobile devices like smartphones and tablets.