The definite article the is the same for all genders in singular and in plural.
the boy, the girl, the cat, the computers
If the following word begins with a vowel, we speak [], if the following word begins with a consonant, we speak [].

[]	[]
the following word starts with a spoken consonant	the following word starts with a spoken vowel
the girl	the English girl
the book	the blue book
the school	the old school
the unit Here a [] is pronounced at the beginning of the word.	the uncle Here a [] is pronounced at the beginning of the word.

We have listed some examples in the following table. There you can see when we use the definite article and when we don't.

without the definite article	with the definite article
general words (indefinite)	general words (definite)
Life is too short. I like flowers.	I've read a book on the life of Bill Clinton. I like the flowers in your garden.
names of persons on the singular, relatives	family names in the plural
Peter and John live in London. Aunt Mary lives in Los Angeles.	The Smiths live in Chicago.
public buildings, institutions, means of transport (indefinite)	public buildings, institutions, means of transport (definite)
Mandy doesn't like school. We go to school by bus. Some people go to church on Sundays.	The school that Mandy goes to is old. The bus to Dresden leaves at 7.40. The round church in Klingenthal is famous.
names of countries in the singular; summits of mountains; continents; towns	names of countries in the plural; mountain ranges; regions
Germany, France; Mount Whitney, Mount McKinley; Africa, Europe; Cairo, New York	the United States of America, the Netherlands; the Highlands, the Rocky Mountains, the Alps; the Middle East, the west of Australia
single islands	groups of islands
Corfu, Bermuda, Sicily	the Bahamas, the British Isles, the Canaries
parks; lakes; streets	name with of-phrase; oceans; seas; rivers
Central Park, Hyde Park; Lake Michigan, Loch Ness; 42nd Street, Oxford Street	the Statue of Liberty, the Tower (of London), the Isle of Wight; the Atlantic (Ocean); the Mediterranean (Sea); the Nile, the Rhine, the Suez Canal
months, days of the week (indefinite)	months, days of the week (definite)
The weekend is over on Monday morning. July and August are the most popular months for holidays.	I always remember the Monday when I had an accident. The August of 2001 was hot and dry.

We use the seasons of the year (spring, summer, autumn, winter) with or without the definite article.
in summer or in the summer
The American English word for autum >fall< is always used with the definite article.

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Sometimes we use the article and sometimes we do not. It often depends on the context. Watch the following example:
The student goes to school.
The mother goes to the school.
In the first sentence we do not use the definite article, in the second we do. The student goes to school for its primary purpose, so we do not use the article.
The mother might talk to a teacher, for example. She visits the school for a different reason. That's why we use the definite article in the second sentence.