What information does a social security number tell you?

Answer 1

The first three numbers will indicate where the person lived when they got the number.

Answer 2

Well... social security numbers are necessary for opening bank accounts, opening credit card accounts, etc. Therefore, the actual number tells you nothing, although, if that number is found, as well as a person's full legal name and their date of birth, identity theft is possible. Social security numbers are usually the hardest to find, due to their lack of use otherwise; this is why it is advisable to never give out your social secuirty number to ANYBODY.

On a separate note, I'm not sure if maybe you were asking what social security is? With every cashed paycheck, a small percentage is taken and stored in social security. Therefore, when you retire, you have a hopefully sufficient amount of money to sustain yourself for the years to come.