The definite article ‘the’ is used:

When we speak of a particular person, place or thing

• I met the Chief Minister yesterday.
• The driver stopped the car.

Before unique objects or natural phenomena

• The sun rises in the east.
• The sky is blue.

Before adjectives of the superlative degree

• India is the biggest democracy in the world.
• Mount Everest is the highest peak in the world.
• She is the prettiest girl I have ever seen.
• Solomon is the best player in the team.
• The cheetah is the fastest animal.

Before the names of sacred books: the Bible, the Koran, the Gita, the Ramayana etc.

Before nouns referring to the people of a country

• The Germans fought against the English in the Second World War.

Before the words first, second, third, last, next etc.

• She is the first woman to win the Nobel Peace Prize.
• The next train arrives at 6.30.

Before a singular noun representing a whole class

• The tiger is a wild animal.
• The rose smells sweet.
• The lion is the king of beasts.

Before an adjective used as a noun

Examples are: the rich, the poor, the jobless, the unemployed, the blind etc.

• The rich should help the poor.
• The unemployed are losing hope.
• They are collecting money for the blind.