PUNCTUATION Punctuation marks indicate relationships among different sentence elements. As a result, these marks help clarify the meaning of written material. The Comma The comma (,) was invented to help readers. Without it, sentence parts can collide into one another unexpectedly, causing misreading. When to use the comma: e When linking two independent clauses with a coordinating conjunction (and, but, or, nor, for, yet, or so), put a comma in front of the conjunction e Use commas to separate words, phrases, and clauses in a series. e Use acomma between coordinate adjectives—that is, adjectives that separately modify the same noun. e Use a comma to separate or set off introductory elements, places and dates, nonrestrictive expressions, and parenthetical expressions. > Class Exercise 22