Using a or an depends on the sound that begins the next word. So…

(1) a + singular noun beginning with consonant: a boy; a car; a bike; a zoo; a dog
(2) an + singular noun beginning with a vowel: an elephant; an egg; an apple; an idiot; an orphan
(3) a + singular noun beginning with a consonant sound: a user (sounds like ‘yoo-zer,’ i.e. begins with a consonant ‘y’ sound, so ‘a’ is used) a university; a unicycle
(4) an + nouns starting with silent “h” : an hour
a + nouns starting with a pronounced “h”: a horse

In some cases where “h” is pronounced, such as “historical,” you can use an.However, a is more commonly used and preferred.

Basic use of a or an:

You were probably taught at school ‘an’ should be followed by a vowel (a,e,i,o,u) and a should be followed by a consonant.

• an elephant
• a car

Unfortunately, this is not always true!

When to use an or a depends on how the word is pronounced and not on how it is written.
The U in university is pronounced with a long ‘u’ sound which sounds like ‘yew’ and is written as jin the phonetic alphabet. So, although the letter is a vowel, it is not pronounced like one in ‘university‘ because it does not have a vowel sound. We therefore say ‘a university’.

The U in umbrella is pronounced as a vowel sound ( Λ using the phonetic alphabet) and so we use ‘an’. We therefore say ‘an umbrella’.

If the noun is modified by an adjective.

The choice between a and an depends on the initial sound of the adjective that immediately follows the article:

• a broken egg
• an unusual problem
• a European country (sounds like ‘yer-o-pi-an,’ i.e. begins with consonant ‘y’ sound).

In the section on pronouns, we saw that the word it is a third person singular pronoun. However, this word also has other roles which are not related to its pronominal use. We look at some of these other uses here.
When we talk about time or the weather, we use sentences such as:

• What time is it?
• It is four o’clock.
• It is snowing.
• It’s going to rain.

“Grammar” means the study of how words and their component parts combine to form sentences, grammar is the system of a language. People sometimes describe grammar as the “rules” of a language; but in fact no language has rules*. If we use the word “rules”, we suggest that somebody created the rules first and then spoke the language, like a new game. But languages did not start like that. Languages started by people making sounds which evolved into words, phrases and sentences. No commonly-spoken language is fixed. All languages change over time. What we call “grammar” is simply a reflection of a language at a particular time.

Grammar is the structural foundation of our ability to express ourselves. The more we are aware of how it works, the more we can monitor the meaning and effectiveness of the way we and others use language. It can help foster precision, detect ambiguity, and exploit the richness of expression available in English. Two different kinds of grammar are used.Descriptive grammar (definition #1) refers to the structure of a language as it is actually used by speakers and writers. Prescriptive grammar (definition #2) refers to the structure of a language as certain people think it should be used.

Grammar is one of the most essential things you should know when you learn to write proper English. It deals with the forms and structures of words and sentences. You should know the proper usage of such words. The best way to learn English grammar is not by using the dictionary but by using English grammar books.  Good writers not only rely on themselves, when it comes to write good copy, abstracts, documents, letters or even books. They rely on supportive tools, like advanced (NLP)  Natural language processing grammar checkers.

 Use of  “the” in English Grammar:

Articles in English are invariable. That is, they do not change according to the gender or number of the noun they refer to, e.g. the boy, the woman, the children

‘The’ is used:

1. to refer to something which has already been mentioned.

Example: An elephant and a mouse fell in love.

The mouse loved the elephant’s long trunk,

and the elephant loved the mouse’s tiny nose.

2. when both the speaker and listener know what is being talked about, even if it has not been mentioned before.

Example: ‘Where’s the bathroom?’

‘It’s on the first floor.’

3. in sentences or clauses where we define or identify a particular person or object:

Examples: The man who wrote this book is famous.

‘Which car did you scratch?’ ‘The red one.

My house is the one with a blue door.’

4. to refer to objects we regard as unique:

Examples: the sun, the moon, the world

5. before superlatives and ordinal numbers: (see Adjectives)

Examples: the highest building, the first page, the last chapter.

6. with adjectives, to refer to a whole group of people:

Examples: the Japanese (see Nouns – Nationalities), the old

7. with names of geographical areas and oceans:

Examples: the Caribbean, the Sahara, the Atlantic

8. with decades, or groups of years:

Example: she grew up in the seventies

We do not use the with:

Television:

• I watch television a lot.
• what’s on television tonight?

•  but   can you turn off the television? (=the TV set)

We do not use the with:

Places ( continents, countries, states, islands, towns etc.)

• France is a very large country. (not the France)
• Cairo is the capital of Egypt.
• Peru is in  South America.

But we use the in names with republic/ states/ kingdom:

THE      the Republic of Ireland ( or the Irish Republic)

the United States of America (the USA)      the United Kingdom (the UK)