Interjections are words or sounds thrown into a sentence in order to express some feelings of mind.
Hurrah! we have won the match.
Heigh-ho! this is a very hot day.
Fie, fie! you should not make such mistakes.
Wow! what a nice dress.
Hush! I have missed the train.
Pooh! I am not afraid of snake.
Alas! he is so sick.
Oh! what a pleasant surprise.
Ah! it was really sad.