LESSON 3. THE DEFINITE ARTICLE "THE"

The definite article is "the"

It is the same for singular and plural and for all genders. 

The definite article "the" is used

1. Before nouns of which there is only one, or which are considered as one.
• Eg. the earth, the weather, the north pole
2. Before noun which has become definite as a result of being mentioned a second time.
• Eg. His car struck a tree. You can still see the mark on the tree.
3. Before a noun made definite by the addition of a phrase or clause.
• Eg. The boy that I met. The place where I met him.
4. Before a noun which by reason of locality, can represent only one particular thing.
• Eg. He sent for the doctor
5. Before superlatives and first/second only,  used as adjectives or pronouns.
• Eg. Most people think that Monday is the worst day in the week.
6. Before singular nouns used to represent a class of objects.
• Eg. The cuckoo is lazy.
7. Before an adjective used to represent a class of persons.
• Eg. The old and the young should be able to live together.
8. Before names of seas, rivers, chains of mountains, groups of islands and plural names of countries.
9. Before musical instruments.
• Eg. She learnt to play the flute.