Date of birth:
The date of birth of an individual indicates the day, the month, and the year of their birth. There are individuals who know the exact date of their birth, there are some who do not know the full date of their birth but know at least the month and the year of their birth.

The age of an individual is the number of years lived by this individual since the day of his birth to today.

The age in years passed expresses the number of whole years lived by this individual since his birth. The age that will be considered is the age in years passed

If we do not know the exact date of birth of an individual, but only the year of his birth, calculate the age at the birthday reached in the year by calculating the difference of years. As such, a person who was born in 2000 will be 5 years old in 2005, meaning he will have reached his 5th birthday in 2005.