An interjection is a word or short phrase that expresses sudden emotion or reaction. When you shout “Wow!” after seeing an amazing magic trick, or “Ouch!” when you stub your toe, or “Hey!” to get someone's attention, you're using interjections. They burst out of us naturally when we feel something strongly.

Interjections stand apart from regular sentence structure. While most words connect grammatically to form complete thoughts, interjections often appear alone or at the beginning of sentences, separated by commas or exclamation points: “Oh, I forgot my homework!” “Hooray! We won the game!” “Ugh, this tastes terrible.”

In writing, interjections help show how characters feel without having to explain it. Instead of writing “Sarah was excited when she opened the present,” you might write “Sarah tore open the wrapping paper. 'Yes!' she shouted.” The interjection makes the emotion immediate and real.

Common interjections include wow, oops, yikes, phew, hmm, aha, and yay. Some are actual words with other meanings (like “well” or “oh”), while others exist purely as interjections (psst, shh, ugh). Different languages have different interjections: English speakers say “ouch” while Spanish speakers say “ay.”

Interjections add personality and feeling to both speech and writing, turning flat sentences into moments that crackle with genuine human emotion.