What are the rules for using indefinite articles in English?

This is the third of four chapters about Articles. To complete this reader, read each chapter carefully and then unlock and complete our materials to check your understanding.   

– Introduce the concept of indefinite articles in English

– Explore when and why indefinite articles are used

– Provide examples for the five uses of indefinite articles

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Chapter 3

Much like for the definite article ‘the’, the indefinite article ‘a/an’ also has some overall guidance that can be applied to most situations. Generally then, the indefinite article is used for singular countable nouns and never plural or uncountable nouns. Such countable nouns using ‘a/an’ are usually yet to have been introduced to the reader within the text, and are not generally obvious to the reader either based on the context. In other words, we use ‘a’ or ‘an’ to introduce an object or concept that our reader may not yet be aware of, such as in the following examples:

Articles 3.1 Indefinite Article 'an'
Articles 3.2 Indefinite Article 'a'

In the first example, the ‘amazing lecture’ is new information to the reader or listener, just as the ‘new classmate’ is in the second example. These noun phrases have therefore been introduced with ‘a/an’ to indicate this fact.

Also noticeable in the above examples is that there is some variation in both the pronunciation and spelling of the indefinite article. Before turning to the five rules of indefinite articles introduced below, it’s first worth mentioning that how this article is spelled and pronounced is dependent on the next immediate sound. For example, when the article comes before a vowel we use /ən/ (‘an’) and when it precedes a consonant we use /ə/ (‘a’), as is shown in the following table:

Articles 3.3 Pronouncing 'a' and 'an'

Notice in the final example ‘an MP3’ that it’s not the spelling of the noun that requires ‘an’ (because of the consonant ‘m’), but it’s the vowel sound that’s produced (/ɛm/) when the word is pronounced that alters the article type.


1. Singular Nouns

Unlike definite articles, indefinite articles may only be used with singular nouns and not with plural or uncountable nouns, such as is shown below:

Articles 3.4 Singular Nouns

However, it’s important to note that with certain uncountable nouns such as ‘milk’ and ‘rice’, the indefinite article may be used if there’s an omitted word indicating singularity, such as in the sentences “Yes, I’ll have a (bowl of) rice” or “Please give me a (glass of) milk”.


2. Introducing Something New

As has been previously explained, one of the most important rules for using the indefinite article is to introduce something new to the reader or listener. Once introduced, it’s then grammatical to instead use the definite article ‘the’ to continue discussing that concept or object.


3. Occupations

Another common (and easy-to-remember) use of ‘a’ and ‘an’ is when describing someone’s job or occupation, such as in the following examples:

Articles 3.5 Occupations
Articles 3.6 Occupations

4. Expressing Time and Quantity

Some expressions describing time and quantity are also commonly used with ‘a/an’:

Articles 3.7 Expressing Time and Quantity

5. Using ‘there is’, ‘have’ and ‘have got’

Finally, it’s useful to remember that the indefinite article ‘a/an’ is also usually used after the expressions ‘there is’, ‘have’ and ‘have got’:

Articles 3.8 Using 'there is', 'have' and 'have got'

Provided you follow all of the general guidance and specific rules we’ve provided in this chapter, you should be using indefinite articles accurately in no time at all. However, there’s still one final aspect of this topic that needs discussing, which is when a zero article is used before a noun phrase instead of ‘a/an’ or ‘the’.

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