Nouns may feature as the subject or object in a sentence. Being the first words that one learns, nouns may be classified as :
Most nouns change their form to indicate number by adding "-s" or "-es" (birds, boxes).
countable nouns have singular and plural forms and can be counted (babies).
Non- countable nouns do not have a plural form and cannot be counted. (oxygen).
Nouns are used before other nouns (Teacher's organisation, Student's association)
Nouns are used as verbs as well (oiled machine, bottled fruit).
Verbs used as nouns are called as gerunds (walking is a good exercise)
1. He works as a teacher (common noun) in a high school
2. Susheela (proper noun) was a singer
3. He was nostalgic about his childhood (abstract)
4. The steering committee (collective noun0 meets every Monday.
5. Since he inherited his uncle's library, he spends every weekend indexing his books.