Before the names of substances and abstract nouns (eg uncountable nouns) used in general sense:
Sugar is bad for health.
Gold is a precious stone.
Wisdom is the grace of God
Honesty is the best policy.
Virtue is its own reward.
However, uncountable nouns take the definite article, the, when used in a particular sense
Would you pass me the sugar, please? (= the sugar near you)
The wisdom of Chandragupta Vikramaditya is great.
I can’t forget the kindness with which he treated me.
Before plural countable nouns used in a general sense:
Children like chocolates
Computers are used in offices.
Note that such nouns take on the when used in a particular meaning:
Where are the children? (= our children)
Before most proper nouns (except those referred to earlier)
Names of people (Gopal, Rahim), places (India, Brazil), mountains (Mt Everest)…
Before names of meals (used in a general sense)
When do you have lunch?
Dinner is ready.
But if an adjective is used then these nouns take on the indefinite article (a/an)
I had a late lunch today.
The dinner at Hyatt was very good.
Before languages:
We study English.
They speak French at home.
With school, college, church, hospital, market, prison, bed, table when these places are visited or used for their primary purpose:
I learnt French at school.
We go to church every Sunday.
He stays in bed till nine.
My uncle’s is still in hospital.
The is used when they are used in the definite sense, rather that the normal activity associated with them:
The school is near my home.
I met him at the church.
The bed is broken.
I went to the hospital to see my uncle.
Before names of relations like father, mother, uncle and cook, nurse (as in our cook, our nurse)
Father has returned.
Aunt wants to see you.
Cook has given notice.
Before positions held by one person for a limited time:
He was elected chairman of the Board.
Mr Bannerji became principal of the college last year.
In certain phrases consisting of a transitive followed by its object:
Catch fire, take breath, give battle, cast anchor, send word, bring word, give ear, lay siege, lose heart, set foot, leave home, strike root, take offence
In certain phrases consisting of a preposition followed by its object:
At home, in hand, in debt, by day, by daybreak, at sunrise, at noon, at sunset, at night, at anchor, at sight, on demand, at interest, on earth, by land, by air, by train, by car, on horseback, ob foot, in jest, at ease, under ground