I pay for everything myself (food, water, car, school, etc-) The only thing I wonder if it counts if i pay rent to my parents. Does that invalidate "supporting myself"?

Are you trying to determine if you can be claimed as a dependent?  Provide some other important information----how old were you at the end of 2023?   Were you a full-time student in 2023?  Did you have more than $4700 of income  (not counting any Social Security) in 2023?

Q. I wonder if it counts if i pay rent to my parents?

A. Yes. Whether you can it rent or sharing expenses, what you pay your parents counts as support you provided for yourself.

Q. Does that invalidate "supporting myself"?

A, No. Just the opposite.  It makes it more likely that you did support yourself. But, you have to offset that by the value of the value of the shelter they provide. 

The support value of the home, provided by the parent, is the fair market rental value of the home plus utilities & other expenses divided by the number of occupants.

The IRS has a worksheet that can be used to help with the support calculation. See: http://apps.irs.gov/app/vita/content/globalmedia/teacher/worksheet_for_determining_support_4012.pdf

What is it, you are trying to accomplish? With the tax law change, effective 2018, most students/dependents will get the same refund whether they claim themselves or not. The personal exemption has been eliminated and the standard deduction increased. Furthermore, most students, under 24, are not eligible for the refundable portion of the tuition credit. It is usually best if the parent claims that credit.