A common noun names any person, place, or thing. It begins with a lowercase letter.
A proper noun names a particular person, place, or thing.
Each important word of a proper noun begins with a capital letter. When we replace a common noun with a proper noun, we need to remove the article before the common noun. The articles are usually a or the.
I will visit a new city next month.
I will visit Rome in July.
common noun: city and month
proper noun: Rome and July
The boy and his grandfather are fishing on the lake.
Charles and Joe are fishing on Lake Simcoe.
common noun: boy, grandfather, lake
proper noun: Charles, Joe, Lake Simcoe
My teacher is reading a story to us.
Mrs. Langdale is reading The Three Little Pigs to us.
common noun: teacher, story
proper noun: Mrs Langdale, The Three Little Pigs