Originally Posted by ucalgary.ca/UofC/eduweb

What is a compound compound sentence?

A compound sentence is composed of at least two independent clauses, but no dependent clauses. The clauses are joined by a comma and a coordinating conjunction, a comma and a correlative conjunction, or a semicolon with no conjunction.

Examples:
He finally read the book , or so I thought.

The two independent clause are joined by a comma and
the coordinating conjunction "or."