In latest years driver's inattention is a prime cause of traffic accidents. Driver in-attentiveness is categorized as: 1) distraction 2) drowsiness. Due to this driver's perception level and decision making capability is decreased and hence control over vehicle of driver goes off. To reduce the accidents due to driver being inattentive it is essential for continuously monitoring the driver and driving behavior and alerting the driver if he gets distracted and drowsy. Research is carried out in this area for decades. In advance if it is possible to identify unsafe driving this would prevent accidents. There are some leading automobile companies those have already incorporated this driver assistance system is discussed in this review. This paper provides an overview of current driver alertness system and different methods of detection of driver being attentive. © 2019 IEEE.