1) Interjections are words that:
- express a feeling. Examples: wow, ouch, darn
- say yes or no. Examples: yes, no, yep, nope
- call attention: hey, yo
- indicate a pause: well, hmmm, ah
2) If the interjection expresses a really strong feeling, it ends with an exclamation point.
Example: Ouch! That hurts!
3) If however the feeling is not that strong, it is set apart from the rest of the sentence by a comma.
Example: Ouch, that hurts.
Attribution to Rebecca Elliot and her book Painless Grammar (c) 2006, 1997
Sentence tips for the IELTS are next.