what is a Noun ?

NOUN
A noun is a word used to name a person, animal, place, thing, and abstract idea.

By example :

Portia White was an opera singer.

Types of Nouns :
- Proper Noun
-Common Noun
-Concrete Noun  
-Abstract Noun
-Countable Noun
-Non-Countable Noun
-Collective Nouns

PROPER NOUN
Always write a proper noun with a capital letter, since the noun represents the name of a specific person, place, or thing. The names of days of the week, months, historical documents, institutions, organisations, religions, their holy texts and their adherents are proper nouns.
By example :

Many people dread Monday mornings.

COMMON NOUN
A common noun is a noun referring to a person, place, or thing in a general sense.A common noun is the opposite of a proper noun.
By example :

According to the sign, the nearest town is 60 miles away.

CONCRETE NOUN
A concrete noun is a noun which names anything (or anyone) that you can perceive through your physical senses: touch, sight, taste, hearing, or smell.
By example :

The judge handed the files to the clerk.

COUNTABLE NOUN
A countable noun is a noun with both a singular and a plural form, and it names anything (or anyone) that you can count. You can make a countable noun plural and attach it to a plural verb in a sentence.
By example :

We painted the table red and the chairs blue.

NON-COUNTABLE NOUN
A non-countable noun (or mass noun) is a noun which does not have a plural form. And not usually count.
By example :
             Oxygen is essential to human life.

COLLECTIVE NOUN
A collective noun is a noun naming a group of things, animals, or persons. A collective noun is similar to a non-countable noun.
By example :

The jury is dining on take-out chicken tonight.