What others have said.
I'm not sure where you're located, but in the US, children up to 4'9" in height, or 13 years of age, must be seated (a site I am associated with) in the back seat. It's the law, and there are fines for not doing so.
Now, how you achieve this will depend on their age. Laws will vary from state to state, but this generally means that children up to 50 lbs will use a car seat. Those who weight more than that will use a booster seat. You can use a booster seat for children between the ages and 4 and 9 and less than 4'9" tall. More than that, and seat belts are still required. Here is a guide from CDC to help you determine which seating solution is best for your child: https://www.cdc.gov/motorvehiclesafety/images/child_passenger_safety/VS_cps_share_image.png
In my own research on the topic, I have read many anecdotal accounts of children whose lives have been saved, or who have been spared serious injury because they were using child safety seats correctly. There is also good research indicating that using child correctly helps reduce the risk of death or injury by up to 70%.
Also note that if you use a rear-facing seat incorrectly and place it in the front seat and an airbag accidentally deploys when turned off, the airbag can easily suffocate a child under 12 years of age.
So, keep your child safe by using the correct seating solution for his or her age and height, and by securing it correctly in the car.