Indefinite Article in English Grammar
An article comes before a singular common noun. It is also used when in a conversation that singular common noun is used for the first time.
A, An are two indefinite articles. A is used before a noun starting with a consonant and ‘an’ is used when the noun starts with a vowel.
For example: I have a cat.
I will say this only when I want to tell some one that I have a cat. However, it is also worth noticing that I will tell this to the person who doesn’t know this fact.
Indefinite nouns: A
A cat. A dog. A building. A fork. A knife. A kitchen.
Indefinite nouns: An
An apple. An umbrella. An ice cube. An elephant. An Orange. An antelope.
Also Remember that language rules were made for speaking and you may find many things spelled in a certain way and spoken in a certain way. For example honest. Honest is spelled with an ‘h’, but pronounced with an ‘o’. So we say an honest man. Hour is a similar word. Spelled with an H but pronounced as Our. So it is an hour. So is Heir.
Similarly, unique starts with a vowel,, but is pronounced you neeq. So we say a unique. University is pronounced similarly and we say a university.