Articles: definite article (‘the’) and indefinite articles (‘a’ and ‘an’)
To review the basic rules, when the person you are communicating with knows specifically which thing you are talking about, put the before the noun.
Pass me the salt (You can see the salt I am talking about)
Give me the trousers I left at your house yesterday (You know exactly which trousers)
Have you been to the dentist? (You know which dentist: your dentist)
But when the person you are communicating with does not know specifically which thing you are talking about, use a or an.
I saw a horse yesterday.
I went to a bar at the weekend.
Specific errors with “the”
We do not usually use an article with continents or countries (e.g. Europe, France). But we do use an article before country names that contain a common noun e.g. state, kingdom. This means we do use the before the abbreviations UK and US:
Incorrect: In US and UK there are many different views.
Correct: In the US and the UK there are many different views.
Incorrect: US and UK are major consumers of coffee.
Correct: The US and the UK are major consumers of coffee.
Note, however, that ‘the’ is required before nationality adjectives (e.g. Japanese/Chinese) when used as nouns:
Incorrect: Americans consume more coffee than Japanese and Chinese.
Correct: Americans consume more coffee than the Japanese and the Chinese.
Incorrect: French love croissants.
Correct: The French love croissants.