Framing : divide stream of bit receive from network layer into manageable data units called frames.
Physical addressing: if frames are to be distributed to different system on the network, this layer add header to the frame to define sender/receiver of the frame. If a frame will be sent to different network, receiver address is the address of the device that connects the network to the next one.
Flow control : If data rate sending from sender is too fast than receiver can take, this layer imposed a flow control mechanism to avoid overwhelming the receiver.
Error control : detect and retransmit damage or lost or duplicate frames detect by trailer.
Access control : when two or more device connect to same link, this layer determine which device has control over the link.