Common nouns are names which are general in nature, not specific or unique names.
They can be...
From the examples above, you must have understood what common nouns are. They are general names. The names given within brackets belong to a different class of nouns called proper nouns because they are specific names.
Whenever we want to say something, we say it about someone or something. That someone or something, called the subject of a sentence in grammar, will have a noun or a pronoun as its most important word.
Common nouns, being general or ordinary names, are more frequently used in the subject than the other type of nouns, namely proper nouns, which are names of specific or unique things.
The first letter of a common noun is not capitalized except if it is the first word in a sentence.
Being uncapitalized is an external sign for recognizing a name as a common noun, except when the word starts a sentence.
There are two types:
Sometimes you will find the name count nouns). These are names of people, places, or things that can be counted (e.g. student, teacher, book, chair, city, village.
A better name is Mass Nouns - sometimes also called Non-count Nouns. These cannot be counted (e.g. milk, water, furniture, gold, wood, glass, work, information).