Articles: A/An/The
Level A1 · Articles & Determiners
Use a/an the first time you mention something, or to talk about one member of a general category: I saw a dog in the park (not a specific dog you both know); she's a teacher (one of many teachers). Use the when both speaker and listener already know which specific thing is meant — because it was just mentioned, there's only one, or the situation makes it obvious: I saw a dog — the dog was barking (now specific, already mentioned). The sun is bright today (there's only one sun). Can you close the door? (the door in this room, obvious from context).
Form: a before a consonant sound, an before a vowel sound — the sound matters, not the letter: Say a university and a European city, because both start with a consonant sound, 'yoo'. But say an hour (the h is silent, so the word starts with a vowel sound) and an MBA (M is pronounced 'em', which starts with a vowel sound even though the letter itself isn't silent). The is the same spelling for singular and plural, and for every noun.
The signals a specific, identifiable thing in several common situations:
- already mentioned: I bought a book. The book was expensive.
- unique / only one: the sun, the internet, the president (of a country, in context)
- made specific by extra information: the man in the blue coat, the capital of France
- obvious from the shared situation: pass the salt, please (the salt on this table)
The most common mistake is using the with a first mention, or a/an with a plural or uncountable noun. Say I saw a dog (first mention), not I saw the dog, unless you've already established which dog. And never say a dogs or a information: a/an only combines with singular countable nouns, never with plurals or uncountables (see 'Zero Article' for what to use instead).
Quick check: if this is the first time the listener hears about it, or it's just one of many → a/an (singular countable only). If you and the listener both already know exactly which one → the. If in doubt, ask: could my listener point to a different one? If yes, use a/an; if no, use the.