A noun is a name of a thing, place, or person, e.g., chair, book, cup, college, teacher, New York, London.

There are two types of nouns: 1) Countable Nouns and 2) Uncountable Nouns.

 A countable noun is a noun that can be counted.

For example, ‘book’ is a countable noun because it can be counted. We can say one book, two books, three books, and so on.

Examples: chair, pen, cup, room, dog, car, bottle, car, table, book, bag.

Singular and Plural Forms of Countrable Nouns:

Since such nouns are countable, they can exist in singular as well as plural form, e.g., book, books, pen, pens.

 For singular nouns, the article ‘a’ or ‘an’ is used.

• The article ‘a’ is used before singular nouns starting with a consonant letter (alphabets other than a, e, i, o, u), e.g., a car, a chair, a table. It is also used before a noun starting with a vowel if it sounds like a consonant, e.g., a university.
• The article ‘an’ is used before singular nouns starting with a vowel letter (a, e, i, o, u), e.g., an apple, an umbrella, an onion. It is also used before nouns starting with a consonant if it sounds like a vowel (when the first letter is mute), e.g., an hour.

 The plural form of a countable noun is made according to the following rules:

• For most nouns, the plural form is formed by adding ‘s’ or ‘es’. Examples: pen – pens, book – books, box – boxes.
• If a noun ends with ‘y’, the ‘y’ is changed into ‘i’ and ‘es’ is added. Examples: lady – ladies, country – countries.
• Plural forms for a few nouns are formed differently. Examples: wife – wives, knife – knives, leaf – leaves, man – men, tooth – teeth, foot – feet, basis – bases, datum – data.
• A few nouns remain the same in singular and plural form. Examples: swine – swine, deer – deer, sheep – sheep.

A noun that cannot be counted is called an uncountable noun.

For example, ‘water’ is an uncountable noun. We cannot say ‘one water’, ‘two waters’, or ‘three waters’. Such nouns cannot be counted in numbers like countable nouns.

Examples: rain, honey, milk, bread, furniture, wheat, information, news, honesty, pleasure, warmth, excitement, love, weather.

• The articles ‘a/an’ are generally not used before an uncountable noun. The article ‘the’ can be used before an uncountable noun only when it refers to a specific thing.
  
  Examples.

• He is drinking a water.              (Wrong)
• He is drinking water.                 (Correct)
  
• Money gives you a power.        (Wrong)
• Money gives you power.           (Correct)

The words such as ‘some, more, too much’ are sometimes used to somewhat specify the amount of an uncountable noun.

• Please give me some water.
• Add some milk in the tea.
• I need some information about the admission process.

Remember, uncountable nouns refer to things in their collectivity and therefore they are mostly treated as singular nouns in a sentence.

• The information are helpful.     (Wrong)
• The information is helpful         (Correct)
• The water in the tank are not clean.       (Wrong)
• The water in the tank is not clean.          (Correct)
  

   Changing an Uncountable Noun into a Countable Noun

Uncountable nouns represent entities in their entirety that cannot be counted in numbers. Sometimes, the context gives an idea of the amount, but the exact quantity is not precise.
Example 1: Water is an uncountable noun.

• “The water in the sea is polluted.” → refers to a large amount of water.
• “He drank water.” → refers to a relatively small amount of water.

However, the exact amount is still not precisely known in terms of numbers or measurable units because of the uncountable nature of the noun. Because uncountable nouns do not have exact numbers, we can make them countable by adding a measurable unit. This allows us to express quantity relatively more clearly.

• Water: one glass of water, two glasses of water
• Tea: one cup of tea, two cups of tea

Here are some examples of using words to specify the quantity or amount of an uncountable noun.

• Uncountable    --- Countable

• Wheat              --- a grain of wheat
• Bread               --- a piece of bread
• Milk                  --- a glass of milk
• Information      --- a piece of information