An interjection is a word or phrase that conveys a sudden emotion or reaction. When employed in a sentence, it often appears alone and is followed by an exclamation mark or a comma. Common interjections are "Wow!" (surprise), "Ouch!" (pain), "Oops!" (error), "Hey!" (attention), and "Yay!" (pleasure). For example, in "Wow! That was amazing," the exclamation "Wow!" conveys excitement. Interjections bring emotion, tone, and spontaneity to speech and writing. They are more typically employed in casual talks than in official writing. Understanding interjections improves expressive communication by making the language more lively and interesting.