what is difference between Für and Fürs?
Thanks for watching (Dankeschön fürs zusehen). In this sentence fürs is being used, why cant we use für? what is the difference between für and fürs? Please help me to understand.
Yes, in this case, the verb "zusehen" is turned into the noun "(das) Zusehen" (which should indeed be written with a capital letter). This is very common in German. Generally, this can be done with any verb.
Ich schreibe. -- "Das Schreiben macht mir Spaß".
Ich lese. -- "Das Lesen fällt mir schwer".
Yes, this way of turning a verb into a noun is productive, meaning you can apply it to any verb, not just a fixed set of traditional ones.
It's more or less like the -ing gerund in English to turn a verb into a noun, e.g. "Singing is fun" or "Smoking kills" or "Rock-climbing is dangerous" or "We like canoeing".