Which indefinite article should precede hour — a or an?
- an hour
- a hour
Does the usage of an vs a depend on the pronunciation — a history, a hobby, but an hour, an honor?
Does the usage of an vs a depends on the pronunciation: a history, a hobby, but an hour, an honor.
Yes. If a word begins with a vowel sound, then the correct article is an; otherwise, if it begins with a consonantal sound, the correct article is a.
Because hour is typically pronounced with a silent h, an hour is correct.
I wrote a blog post about an vs a on the EL&U blog some time ago, and it covers a wide variety of other cases that you might be interested in.
An hour is correct, because "hour" begins with a vowel sound. A vs. an depends on pronunciation, not spelling.
Some notable cases: