Both are acceptable, depending on context. For example:
Fishing bait is useful to fisherman.
Fishing bait is useful for catching fish.
I would not say they are useful. But they make nice pets.
gebruik
Scarfs
Helpful
muy util
don't do crimes
Useful is not a noun or a verb, it is an adjective. Adjectives are descriptive words used to describe nouns. For example, if you say, "the useful dog," useful is the adjective modifying dog, the noun.
You used modern equipment (a computer) to post this question, I would say that is useful to you.
zinc is an essential mineral that keeps you healthy...I'd say that's pretty useful.
This can be quite debatable. Some people would say it was useful as it ended WW2 in the Pacific after Germany surrendered but some would say it wasn't useful as the use of the atomic bombs was 'out of order' and 'over the top'. The usefulness depends on how you look at it and where would it be useful.
The are important and useful but I would not say that they are famous!
It helps you when you say what subjects you dofor a University