Indefinite Article

The indefinite article is relatively easy to learn as there are but three of them and their rules are easy enough to understand.

Problems can sometimes arise for those who don't clearly understand the 'exceptions to the rules.'

And as the case seems to be with many rules, English articles also have what we call, 'exceptions.'

Exceptions mean that sometimes the rules don't apply and then there are new, or different, rules that apply for that particular instance.

Don't worry, though, the rules and exceptions for the indefinite article aren't that difficult to remember, and at the advanced level of the English language they should require just a quick review which just happens to follow...

Indefinite article: 'a, an' 

These English articles are used before singular nouns. They specifically relate to any member of a group.

Ex: A dog is in the street. 

Difficulties and 'exceptions' with English Language articles...

Use 'an' instead of 'a' when it comes before a vowel sound NOT just before a word that begins with a vowel.

Ex: We say; "It's an honor to meet you" NOT "It's a honor to meet you."

Why? Because the 'h' in honor is silent.

Ex: We say; "My dad belongs to a union" NOT "My dad belongs to an union."

Why? Because 'union' is pronounced (you nee un.) 

'H' sounded or silent? -- plus -- where's the accent?

The 'h' can cause some problems if you don't know the following. Words beginning with 'h' can be preceded by 'an' or 'a' depending on where the accent in the word is...

Ex: I have a history lesson at 10:00am. (first syllable in history accented)

Ex: It was an historic occasion. (second syllable in historic accented) 

Ex: An honor to meet you. (silent)

Ex: Is that a hypothetical question? (sounded)

Indefinite article with abbreviations 

Acronyms and abbreviations can be problematic for those who don't know the above. Depending on how the acronym is pronounced, it can be preceded by either a or an.

Ex: A CNC lathe. (pronounced see en see)

Ex: An MRI. (pronounced em ar eye)

Ex: A UNC basketball game. (pronounced you en see)

For more information regarding the indefinite article click on the preceding link.