(1) Polling is a CAM. In a master/slave scenario, the master queries each slave device in turn as to whether it has any data to transmit. If the slave answers yes then the device is permitted to transmit its data. If the slave answers no then the master moves on and polls the next slave device. The process is repeated continuously. Also see contention and token passing.
(2) Making continuous requests for data from another device. For example, modems that support polling can call another system and request data.