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 instance, ‘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.

 Since such nouns are countable, they can exist in singular form as well as plural form.

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, etc. It is also used before nouns starting with a consonant if it sounds like a vowel (such as that in some cases the first letter is mute). e.g., an hour.

The plural form of a countable noun is made according to the following rule.

• 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 to it for making its plural form. 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 also 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 instance, ‘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.

Article ‘a /an’ is 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 but they are mostly treated as a singular noun 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

An uncountable noun generally refers to a thing in its entirety. The context, where it is used, may give some rough idea about its amount. For instance, water is an uncountable noun. When we hear a sentence such as ‘The water in the sea is polluted’ we can guess that this refers to a fairly large amount of water. By contrast, when we hear a sentence ‘He drank water’ we can guess that this refers to relatively a very small amount of water. However, the amount is still not accurately known because of the nature of the noun ‘water’ – an uncountable nature.

Therefore, to be relatively more accurate about its amount, an uncountable noun may be converted into countable form by using somewhat measurable unit for it. For instance, the uncountable noun ‘water’ can be converted into countable noun by saying one glass of water or two glasses of water. Similarly, for uncountable noun ‘tea’ it can be said like one cup of tea or 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