Articles are either definite or indefinite. They are before a noun to indicate the type of reference being made by the noun.

• The definite article is the.
• The indefinite article is a or an or some.

The indefinite article a or an

The article a / an is used when we don’t specify the things or people we are talking about:

• I met acolleague to discuss my dissertation.
• I work in alaboratory in Shanghai.
• I wrote a poster with acolleague from my department.

The indefinite article a is used before a consonant sound:

• apiece of research
• a researcher
• ascatter graph
• ateacher
• auniversity

The indefinite article an is used before a vowel sound:

• anengineer
• anexperiment
• anexample of
• an obstacle
• an item of

The definite article the

The definite article is used when the speaker talks about a specific object that both the person speaking and the listener know.

• Theposter won a prize at the
• Thepresident of the Association will make the final presentation.

When we speak of something or someone for the first time we use a or an, the next time we repeat that object we use the definite article the.

• We used a control group in the study. Thecontrol group included 50 patients.
• I presented my poster at aThe conference had a large number of delegates.

No article

In English we do not use an article with countries, states, counties or provinces, lakes and mountains except when it is included in the name, e.g. The United States.

• We carried out our research in England and France.
• They are based in North America.
• The research was mainly conducted in Brazil.
• All the species were found in The

We do not normally use an article with plurals and and uncountable nouns:

• We collected water to be used for…
• We found evidence to suggest that…
• We submitted five articles covering the research.
• Our research team consisted of researchers from several countries.

Countable and uncountable nouns

Using English articles with countable and uncountable nouns may be confusing.

The can be used with uncountable nouns, or the article can be dropped entirely as above.

We published the research in a high-impact journal (some specific research). Or: We published research in a high-impact journal (any research).

She read the article (some specific article that we know about) or She read an article (any article).

It is unusual to use a/an for uncountable nouns. You can’t say we used a software.

a/an can be used only with countable nouns.

We used a piece of software to measure our results.

An engineer was used to set up the …

The indefinite article some

We use the indefinite article ‘some’ for the plural form of all nouns and for uncountable nouns.

When we first ran the experiment we had some initial results.

You will need some equipment to carry out the research.

I found some evidence to prove my hypothesis.

Read through the extract below and look at how the various articles are used – can you identify each rule?

Try the short multiple-choice quiz below to test your knowledge.