A common noun is a word
that names people, places, things, or ideas. They are not the names of a single person, place or thing.
A common noun begins with a lowercase letter unless it is at the beginning of a sentence.
For example:-
People:-
man, girl, boy, mother, father, child, person, teacher, student
Animals:-
cat, dog, fish, ant, snake
Things:-
book, table, chair, phone
Places:-
school, city, building, shop
Ideas:-
love, hate, idea, pride