"An" is used before words that start with:
* A vowel sound:
* Example: "an apple," "an orange," "an hour"
* Note: The "h" in "hour" is silent, so it begins with a vowel sound.
* A silent "h" followed by a vowel sound:
* Example: "an honor," "an honest person"
"A" is used before words that start with:
* A consonant sound:
* Example: "a cat," "a book," "a university"
* A vowel sound that begins with a consonant sound:
* Example: "a unicorn," "a European"
Important Note:
* The sound of the word is what determines whether you use "a" or "an."
* If you're unsure, say the word out loud and listen to the initial sound.
Let me know if you'd like more examples or have any other questions!