A new set of guidelines from the American Academy of Pediatrics suggests involving parents heavily during young childhood media exposure and using any media exposure throughout childhood as a support for family bonding, social skills, and learning.
The guidelines give different advice for children under the age of 18 months (almost no screen time), between 18 months and 3 years (limited screen time with family), between 3 and 5 years (educational supervised screen time), and between 5 and 18 years. They are heavily differentiated by age during toddlerhood because of the intensive social, emotional, and intellectual development occurring during that time.
After toddlerhood, the important message is to use media to bolster children's real-world development and help them enjoy time they should already be spending with their family and friends. Media use should almost never replace physical activity, screen-free academic study, or in-person interactions. The American Academy of Pediatrics provides an online tool called the Family Media Plan to help shape screen time so that it remains healthy.