But, when writing, or editing, especially in narrative, we really need to be technically correct as far as is possible. In dialogue, grammatical errors and dialect are fine, if that is how your character speaks. But in narrative, we have to be more careful.
Dictionaries are not always reliable, as they reflect common usage rather than correct usage. As language evolves constantly, it is a fact that, when enough people get it wrong, it will inevitably become 'right'. Be that as it may, at this point in time, our writing must reflect what is currently 'right'.
This is the first in a series of daily tips on good usage vs. common usage.
We were all taught at school to use 'a' before a consonant and 'an' before a vowel. So, such constructs as "a cow" and "an elephant" pose no problems. But what do we do when a word begins with, for example, a vowel, but sounds as if it begins with a consonant, and vice versa?
We go with the sound of the word, not the spelling, as the a/an difference undoubtedly evolved for ease of speech.
So, use the indefinite article 'a' before any word beginning with a consonant sound e.g. "a utopian dream". Use 'an' before any word beginning with a vowel sound e.g. "an officer", "an honorary degree".
The word "historical" and its variations cause missteps, but since the 'h' in these words is pronounced, it takes an 'a' e.g. "an hour-long talk at a historical society".
Likewise, an initialism (whose letters are sounded out) may be paired with one article while an acronym (which is pronounced as a word) beginning with the same letter is paired with the other e.g. "an HTML website for a HUD program".