When it comes to car seats, age is an important factor in determining when you should stop using them. Generally speaking, a child should remain in a car seat until they reach the appropriate height and weight limits as listed on the car seat label. This typically means using a rear-facing infant or convertible seat up to at least two years of age (or until your child outgrows the limits of that particular model). Once your toddler reaches 40 pounds and/or 40 inches tall, he or she can be transitioned to a forward-facing harnessed seat. After this point, depending on their size and maturity level, children will usually move into either a booster seat or directly onto adult safety belts. It's best if your child remains in their booster seat for as long as possible because it properly positions the lap belt low across their hips and shoulders so that they're well-protected during an accident. To ensure maximum protection for all passengers in your vehicle, always read the labels of any new car seats carefully before use; follow manufacturer instructions exactly; register products with manufacturers' recall programs; keep updated records of usage dates and expiration dates; replace expired seats immediately; avoid buying used restraints without proper documentation from previous owners about its history; take extra precautions if riding with pregnant women or medically fragile passengers; and never place an infant carrier on top of shopping carts!