The document discusses common errors in joining independent clauses, specifically fused sentences, comma splices, and run-on sentences. It explains that the three correct ways to join two independent clauses are with a period, semicolon, or comma plus a coordinating conjunction. Comma splices incorrectly use only a comma, while run-on sentences incorrectly use only a coordinating conjunction. The document provides examples and explanations of each error type and how to fix them.