A visitor wrote in to ask when to use “a” and when to use “an.” In particular, she wanted to know which of the following is correct:
- Citibank is a MNC Bank
- Citibank is an MNC Bank
The correct sentence is number 2.
Use “a” when the following word begins with a consonant sound; use “an” when the following word begins with a vowel sound. What matters is how the following word is pronounced, not what it looks like. In the example sentence, “MNC” begins with a consonant, but it begins with the sound of the vowel “e,” since we would pronounce it as “em en see.”
Some people, especially those who are trying extra hard to sound erudite, will use “an” before a word that begins with the letter “h,” such as “an historical artifact.” In the United States, this usage is incorrect. Instead, we write, “a historical artifact.” For a more detailed discussion of this issue, see “More on A vs. An” from Bill Walsh’s Sharp Points.