I read a book. √ I read book. x This is true even if there are **adjectives** before the noun: He drives an old car. √ He drives old car. x **Never** use a or an with a word that is plural (e.g. books, trees) or uncountable (e.g. water, advice): I asked her for advice. √ I asked her for an advice. x Note that we use a in front of words that start with a **consonan**t sound (a horse, a carrot) and an in front of words with a vowel sound (an apple, an elephant). The next most important thing to understand is the difference between a/an and the. Basically, we use a/an when we don’t need to say which thing we are talking about. We use the to talk about a **specific** thing: I caught **a train** to London. (it doesn’t matter which train) **The train** was late. (that particular train was late) We often use a when we mention something for the first time, and then change to the when it is **clear** which thing we are talking about: He was talking to **a man**. **The man** was laughing. She gave him **a present**. **The present** was very expensive. We also use the when it is **obvious** which thing we are talking about or when there is only one of something: Could you shut **the door**, please? I cleaned **the bathroom** this morning. He travelled around **the world**. **The sun** is hot today. If you stick to the rules above, you will be correct in almost all cases. However, there are a few **exceptions**, and the following are the most useful ones to learn: We don’t use a/an before the names of meals: We had lunch at noon. We don’t use a/an before words like school, prison, or college when we are talking about them in a** general** way: I hope to go to college. He spent three years in prison. With the word ‘hospital’, there is a difference between **British and American English:** My brother’s in hospital (UK) / in the hospital (US). We use the before the names of shops or places where we go for services when they are the ones we **usually** go to: I need to go to the supermarket. She went to the doctor’s.