In many countries citizens and residents are assigned some sort of an identification number. This may be used not only for personal identification but also for taxation and medical care. In the United States, citizens receive what is called a Social Security number.
Paljudes maades omistatakse kodanikele ja alalistele elanikele mingisugune unikaalne numbrikombinatsioon, mida lisaks isiku identifitseerimisele võidakse kasutada maksude tasumisel ja arstiabi saamisel.