In order for your parents to claim you as a qualifying child (and therefore a dependent) they need to have you meet these requirements:
“Relationship – the taxpayer’s child or
stepchild (whether by blood or adoption), foster child, sibling or stepsibling,
or a descendant of one of these.
Residence – has the same principal residence as the taxpayer for more
than half the tax year. Exceptions apply, in certain cases, for children of
divorced or separated parents, kidnapped children, temporary absences, and for
children who were born or died during the year.
Age – must be under the age of 19 at the end of the tax year, or
under the age of 24 if a full-time student for at least five months of the
year, or be permanently and totally disabled at any time during the year.
Support – did not provide more than one-half of his/her own support for
the year.”
If they did not provide more than 1/2 your support and/or you did not live with them for more than half the year, they cannot claim you as their dependent.
A student at school is considered as still living at home in most situations, but not if you left home for reasons other than school and you have no intentions of returning when you are finished with your classes.
Just because you are their child does not mean your parents can automatically claim you as their dependent.
As a side note- this year there is no exemption amount for claiming a dependent.
