Final answer:
An adult is someone 18 or older, a child is between 2.5 and 13, and an infant is from birth to 2.5 years old.
Step-by-step explanation:
Adult: A person who has reached the age of legal majority, typically 18 years or older. For CPR, this is generally defined as individuals aged 12 years and older. The recommended compression depth, compression rate, and other CPR techniques may differ for adults compared to children and infants.
Child: An individual between the ages of 2.5 and 13. For CPR, this is typically defined as individuals aged 1 to 12 years.
Infant: A human being from birth to the age of 2.5 years. CPR techniques for infants, including compression depth and ventilation, are different from those used for children and adults.