When people think about age, it’s usually in terms of how many years one has lived on earth. However, your body can be a different (biological age) from the automatic age (chronological) you get based on the number of years you have been alive.
Chronological age refers to the number of years you have lived while biological age is how old the body acts and how old a person seems. One of the major determinants of biological age is the telomeres in our bodies.