Noun:

Noun: 
Name of anything like person, animal, place, thing, abstract, idea, action, state or quality is called Noun.

Example:
Maria, Girl, Dhaka, Book, Teacher, Water, Honesty, Happiness, Family, Sleep, Death etc.
In Sentence: (Bold words are noun)
- A boy is coming towards us.
- Sarah is a pretty girl.
- The sun shines in daytime.
- Education removes darkness.
- Poverty is curse.

Function of Noun: 
Noun plays the role in a sentence as subject of a verb or object of a verb or both subject and object of a verb.

Classification of nouns:
Noun can be classified into five categories:

1.   Proper noun

2.   Common noun

3.   Collective noun

4.   Abstract noun

5.   Material noun

i. Proper Noun:

Proper noun is the name of some particular person, place or things.

Example:- Dhaka is the capital of Bangladesh. ( Dhaka is the name of one particular capital)
- Sunny is a smart boy. ( Sunny is the name of one particular boy)
- Rimi is a clever girl. (Rimi is the name of one particular girl)

Proper noun always starts with capital letter.

ii. Common Noun:

Common noun is a noun that is not the name of a particular thing or class but that represents one or all of the members of that class or thing.

A common noun can be preceded by the definite articles (a, the).

Example:
- Sunny is a smart boy. (Here boy is common noun while Sunny is a proper noun)
- Rimi is a clever girl. (Here girl is common noun while Rimi is a proper noun)

Example without sentence:
- People: boy, girl, mother, father, baby, child, teacher, student, man, woman etc.
- Things: book, table, computer, pen, pencil etc.
- Animals: bird, dog, cat, cow, goat, wolf, tiger etc.
- Place: city, country, state, capital, beach, forest etc.

iii. Collective Noun:

A collective noun is the name of a collection or number or group of things or persons taken together and considered of as one whole.

Example:
- The navy is the ready for the voyage.
- Public was not aware for the incident.
- The proposal was approved by the cabinet.

Example without sentence:
Crowd, class, army, mob, gang, team, jury, family, herd, committee, audience, council, public, navy, cabinet, group, company, society, troupe, corporation, senate, faculty, board etc.

iv. Material Noun:

A material noun is the name of material, substance or ingredient of things.
Such as iron, steel, copper, gold, coal, silver, milk, water, tea, sugar, wheat etc.

Example:
- The necklace is made of gold.
- The cow gives us milk.
- Give me a cup of tea.

v. Abstract Noun:

An Abstract Noun is usually the name of a quality, action, state or concept. 
Abstract noun are the names of such things those can’t be touched, tested, smelt or heard.
Such as:
Quality- honesty, beauty, bravery, wisdom, heroism, stupidity, darkness, kindness, goodness, brightness etc.
Action- Judgment, movement, laughter, hatred, theft etc.
State- Childhood, boyhood, youth, death, poverty, slavery, sickness, sleep etc.

The names of Arts and Science such as grammar, chemistry, physics, music etc. are also abstract noun.