Not sure what you mean by where does it go -
But, for driver's licenses, the magnetic strip contains:
Name (first, last, middle)
Address
State
City
Postal Code
Date of Birth
Weight
Height
Sex
Driver's license number / State ID number
Hair color
Eye color
Disability (yes or no, for parking)
Some States can utilizae the strip for law enforcement officers to swipe it to populate ticketing or accident forms. Some stores can utilize it to retain and verify information if you provide them a check.

