1. Exceptions It’s important to note that not all nouns that begin with a consonant begin with the consonant sound. Always trust the sound, not the letter when applying the a vs. an rule. Remember, it’s about pronunciation.
1.1. - a hourglass (incorrect) - an hourglass (correct) - a honor (incorrect) - an honor (correct)
2. In English, the two indefinite articles are a and an. Like other articles, indefinite articles are invariable. You use one or the other, depending on the first letter of the word following the article, for pronunciation reasons. Use a when the next word starts with a consonant, or before words starting in u and eu when they sound like you. Use an when the next word starts with a vowel (a,e,i,o,u) or with a mute h.
2.1. EXAMPLES a boy an apple a car a helicopter an elephant a big elephant an itchy sweater an ugly duck a european a university a unit an hour an honor
3. The indefinite article is used to refer to something for the first time or to refer to a particular member of a group or class. Some use cases and examples are given below. Use a to refer to something for the first time.
3.1. EXAMPLES Would you like a drink? I've finally got a good job. An elephant and a mouse fell in love.