A simple sentence contains only one independent clause, which means it has a subject and a predicate, and expresses a complete thought. It does not include coordinating conjunctions (which would indicate multiple main clauses) or subordinate clauses (which would indicate additional dependent elements). An example of a simple sentence is: "The dog barked."
In contrast:
- A compound sentence contains two or more independent clauses joined by coordinating conjunctions (e.g., "and," "but").
- A complex sentence contains one independent clause and at least one subordinate (dependent) clause.
So, to summarize, a simple sentence has one main clause and no coordinating or subordinate clauses.