Other forms: comma splices
When you incorrectly join two independent clauses in a sentence using only a comma, that's a comma splice. An example of a comma splice is "My cat is smart, she can open the refrigerator."
To correctly connect two or more independent clauses in a single sentence, you can use a semicolon; a colon; or a comma followed by a coordinating conjunction (like and or but). But if you just use the comma, and leave out the coordinating conjunction, you've made the error known as a comma splice. Your English teacher will not be pleased! So don't write, "I like chocolate, my brother likes vanilla." Instead, add the word and to correct the comma splice: "I like chocolate, and my brother likes vanilla."