'thanks to' vs 'thank to'

[oboeteru]

I'm wondering about the difference between thanks to and thank to.
Usually when I see such a phrase somewhere in the text it's thanks to, but I don't have any idea why not thank to.

Shouldn't I look at it like at Present Simple? I'm maybe wrong but it's the only idea that came to my head. For giving an example:
Thanks to him I succeed the exam.
But then for plural wouldn't it be:
Thank to my sisters' help I succeed the exam.
?

I'd be really greateful for explanation that will allow me to truly understand it and not just taking it cause it's ALWAYS that way. ;)

[5jj]

'Thanks' is a plural noun with a similar meaning to 'gratitude'. We never give 'thank', only 'thanks'.