The document discusses methods for estimating a person's age based on biological and behavioral markers. The most important biological markers are general development in children, secondary sexual characteristics, teeth examination, and ossification centers. Age can be estimated from birth to adulthood based on developmental milestones, skeletal growth, dental development, and the closure of epiphyseal plates. Specific ages are associated with physical and legal milestones like education, criminal responsibility, marriage, voting, and retirement. X-rays of bones can provide a more precise age estimation.