Centrals and Peripherals are the two key players in Core Bluetooth framework. Peripherals are devices that serve useful data. Centrals are devices which use the information from peripherals to perform useful task. Peripherals advertise their presence by sending small packets of data. The central scans for any near by peripheral devices and when it gets connected to it, it explores and uses the information provided by Peripheral device. Peripheral is responsible for responding to central in appropriate way.