A simple sentence contains one independent clause.
What’s an “independent clause”? It’s one subject followed by one verb or verb phrase. It expresses a single idea.
Examples of simple sentences:
Notice that a “simple sentence” isn’t necessarily short. The subject can be a single word like “I” or “Robert,” or it can be a double subject like “my brother and I,” or it can be multiple words describing a single person/object, like “This new laptop computer.”
A compound sentence has two independent clauses joined by a linking word (and, but, or, so, yet, however).
Each independent clause could be a sentence by itself, but we connect them with a linking word: