A SIMPLE SENTENCE is a sentence consisting of only 1 clause, with a single subject and predicate.
A COMPOUND SENTENCE is a sentence with more than 1 subject or predicate.
A COMPLEX SENTENCE is a sentence containing a subordinate clause or clauses.
A RUN-ON SENTENCE is a sentence in which 2 or more independent clauses are joined without an appropriate conjunction or mark of punctuation.
A SUBJECT of a sentence is the person, place, thing, or idea that is doing or being something.
A PREDICATE of a sentence is the part of the sentence or clause containing a verb and stating something about the subject.
A CLAUSE is a group of related words that contains both a subject and a verb.
An INDEPENDENT CLAUSE expresses a complete thought, so it can stand alone.
A DEPENDENT CLAUSE / SUBORDINATE CLAUSE expresses only a part of a thought, so it can't stand alone.
This sentence IS a COMPOUND sentence because it has 2 predicates, which is more than 1. Even though it has only 1 subject, it is still a compound sentence.
This sentence is NOT a SIMPLE sentence because it has more than 1 clause.
This sentence is NOT a COMPLEX sentence because it does not include any subordinate clauses.
This sentence is NOT a RUN-ON sentence because even though it has 2 clauses, they are joined by a semicolon, which is an appropriate mark of punctuation.