A comma splice results from placing only a comma between independent clauses—groups of words that can stand alone as a sentence. We often see comma splices used to give slogans a catchy rhythm.

Dogs have owners, cats have staff.

—Bumper sticker

A related construction is a fused sentence, or run-on, which results from joining two independent clauses with no punctuation or connecting word between them. The bumper sticker as a fused sentence would be “Dogs have owners cats have staff.”

In academic and professional English, using comma splices or fused sentences will almost always be identified as an error.