A noun is a word which is used as the name of anything for example a place, a city, a thing, a person, etc.
Categories of Nouns:
A) Common Noun - is a common name to every one of the same class or kind. For example, man, woman, boy, book, table, etc.
B) Proper Noun - is a special name of a particular place, thing, etc. For example China, Everest, Nile, John, Rex Cinema, etc. A proper noun begins with a Capital Letter.
C) An Abstract Noun - is the name of something that we can only feel but cannot touch. For example, beauty, truth, wisdom, happiness, etc.
D) A Collective Noun - is the name of a number of persons or things grouped as one. For example, an army of soldiers, a board of directors, a choir of singers, a class of students, etc.