My friend is a doctor.

He is a famous writer.

A proper noun is a noun that refers to a specific person, place, or thing.

Watching the setting sun sink into the sea, I felt at peace.

I mailed a letter at the post office.

Nuclear fusion is expected to be a future energy source.

Organic solvents play an important role in chemical reactions.

We went to the park in the center of the city.

The culture of Central Europe is very rich, and many people enjoy it.

He is an excellent shortstop, contributing greatly to the team's victory.