Independent clauses each have a subject and a verb and could stand alone as a grammatically correct sentence. For instance, “I enjoy walking on the beach,” “I disliked the hot humid weather,” and “I presented at a legal writing conference in Florida last summer” are all independent clauses. Each idea is a complete package; it has a subject and a verb and can function as a sentence. How I link them together with punctuation, however, can subtly change their meanings and shift the emphasis for the reader. It can also help the reader better understand how my ideas are related. [excerpt]
Tenielle Fordyce-Ruff, Creating Separation and Emphasis in Your Writing Part I: Joining Independent Clauses, 54(2) Advocate 44 (2011).