Refers to the method U.S. immigration agencies use to count an overstay. Once a valid visa expires, unlawful presence may start accruing for someone 18 years old or older. However, for those with student visas, unlawful presence starts accruing only if a judge or an immigration official has deemed that the person is unlawfully present. Note that unlawful presence does not accrue for people who are 17 years old or younger.