a

The most useful letter of the alphabet, a – along with its companion an - is called the indefinite article.

The sound of the next letter determines whether a or an is appropriate.

Consonant sounds call for a (a book, a pen, a unicorn), even when the next word begins with a vowel. Items you can count are often preceded by a when there is only one (a fish, a night), but items you can’t count don’t need a or an (pork, news).

A precedes number words to indicate quantity (a dozen rolls, a million dollars), as well as singular words that express quantity (a bushel of corn, a hectare of land).