The indefinite article a/an

We use a/an with nouns when referring to an unspecified thing. - We saw a nice play.
The indefinite article is used:
- with sg countable nouns;
- when we talk about things in general;
- after the verb to be when we want to say what smb/smth is;
- with certain phrases to show how often someone does smth: He sees a therapist once a week.
- before Mr/Mrs when we refer to an unknown person. - A Mr Bauer was asking for you.

The indefinite article is NOT used:

• with uncountable or plural countable nouns, we use some instead.

• before an adjective when there is no noun after it.

The definite article THE

We use the:
- with nouns when talking about smth specific;
- with nouns that are unique (the moon, the Arctic);
- before the names of rivers (the Nile), seas (the Dead Sea), oceans, mountain ranges (the Alps), deserts, groups of islands, countries when they include words such as ”state”, ”kingdom” (the United Arab Emirates);
- before the names of musical instruments (the piano);
- before the names of hotels (the Ritz hotel), performance venues/cinemas, ships, organisations, newspapers and museums;
- before nationalities ending in ”sh” (the Scottish), ”ch” (the Dutch), or ”ese” and families (the Smiths).

• before titles of the person's name is not mentioned (the King);

• before the words morning, afternoon and evening;

• with adjectives in the superlative form;

• with the words: station, cinema, shop, village, world;

• with historical periods/events;

• with the words only, last, first.

We don't use "the" with:

• with plural nouns when we talk about them in general;

• before proper names;

• before the names of countries, cities, mountains, streets, islands, lakes and continents;

• before the names of meals;

• with the words: this/that, these/those;

• with possessive adjectives or the possessive case;

• before titles when the person's name is mentioned;

• with the words school, church, bed, hospital, prison, bed;

• with languages;

• with the names of illnesses;

• with the words home, father/mother when we talk about our own home.