Interjection

The part of speech that expresses strong feeling or sudden emotions or sentiment is called interjection or exclamation.

Example:

- Oh no, I missed the schedule of the class. (Express failure)

- Hey! Don’t you hear me? (Calling attention)

- Hey! Take it easy. (Calling attention)

- Uh, I forget the answer. (Express hesitation)

- Hurrah! We have won the match. (Express joy)

- Wow! She is amazing. (Express surprise)

Note: Interjections are not grammatically related to any other part of the sentence.