'A'/'An' vs. 'The'

There are two articles, 'a' (taking the form 'an' before a noun starting with a vowel sound) and 'the'. There is also a third option of no article. Which of the three choices you use is dependent upon the noun the article points to, as well as the context.

Check out the images below for a breakdown of when to use ‘a’ or ‘an’ (yellow on the left), when to use ‘the’ (blue in the middle), and when to use no article (pink on the right).