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.