Delta infant policy allows infants under two years of age to travel on an adult's lap for free on domestic flights, making it a cost-effective option for families. For international flights, Delta offers a discounted fare for lap infants. Parents also have the option to purchase a separate seat for the infant, provided they use an FAA-approved car seat. Delta recommends reviewing their car seat guidelines and suggests booking directly to confirm specific seating and safety requirements for infants. This policy ensures flexibility and safety for families traveling with young children.