I completely agree with Hannah! I would just like to add a bit more to her answer: 1.- If the following word after the "a" or "an" is an "H", it will depend whether it is pronounced or silent. For example "a helicopter" and "an hour" 2.- The rule depends on the sounds, not whether it is a vowel or not. This means that some words start with a vowel, but make a consonant sound, for example "university" /ˌjuːnɪˈvɜːsəti/, then it would be "a university" So number 2 might be the answer to your question. I hope this was useful, greetings from Mexico! Ps. If you have follow up question or other questions, don't hesitate in sending a private message and I'll be happy to answer!

"a university" because the "u" has the sound of a consonant "an uncle" because the "u" has the sound of a vowel. "an hour" because the "h" has the sound of a vowel. "a hotel" because the "h" has the sound of a consonant. The sound that the first letter of a word makes is the important thing to remember. If the word begins with a vowel sound then we use "an". If the word begins with a consonant sound then we use "a".

You always write “an“ before a noun/adjective which starts with a,e,i,o,u. An elephant An exciting moment You use “a“ before a noun/adjective which starts with another letter (NOT a,e,i,o,u). A cat A big house I hope I could help you!

The rule is a phonetic rule. If the indefinite article "a" is before a word that begins a vowel sound, the "a" become "an." Examples: an apple an elephant an elegant house an ill child an orange an hour (the h is silent) a university (university begin with "y" sound - "yuniversity") an old university