Here's the breakdown:
Traditional Grammar Rule:
The traditional rule is to use "an" before words that start with a vowel sound, even if the first letter is a consonant.
* Examples:
* "an hour" (the "h" is silent, so the word starts with a vowel sound)
* "an honest man" (the "h" is silent, so the word starts with a vowel sound)
Modern Usage:
However, modern usage is becoming more flexible, and some people choose to use "a" before words that start with a vowel sound but have a pronounced "h".
* Examples:
* "a historic event"
* "a hotel"
In short:
* Traditional rule: "an" before vowel sounds, even if the word starts with a consonant.
* Modern usage: "a" or "an" depending on preference, especially for words with a pronounced "h".
Ultimately, it's a matter of style and personal preference. Both options are generally acceptable.