A lot of adjectives are made from verbs by adding -ing or -ed:
The commonest -ing adjectives are:
amusing shocking surprising frightening interesting disappointing exciting tiring worrying boring terrifying annoying
If you call something interesting you mean it interests you.
If you call something frightening you mean it frightens you.
I read a very interesting article in the newspaper today.
That Dracula film was absolutely terrifying.
The commonest –ed adjectives are:
annoyed bored frightened worried tired closed excited delighted disappointed
If something annoys you, you can say you feel annoyed. If something interests you, you can say you are interested.
The children had nothing to do. They were bored.