Understand conventions for using commas and appreciate the likely effects of particular sentence lengths and patterns on reading comprehension.

Commas are like pawns in chess: They seem relatively insignificant and unobtrusive, yet they are actually very important. If properly placed, the lowly pawn can checkmate the king or, once it has reached the end of the board, become a more powerful piece. Commas play an extremely important role in ensuring that your documents are understandable. In fact, failing to insert a comma in the correct spot can cause considerable misreading (and subsequent embarrassment). Beyond a few special circumstances, there are six basic ways to use commas correctly.

"Use Commas after Conjunctive Adverbs and Transitional Phrases at the Beginnings of Sentences" was written by Joe Moxley.

Although our modern style calls for using as few commas as possible, you should generally place a comma after conjunctive adverbs and transitional words because they modify the entire sentence:

• Nevertheless, we must push forward with our plans.
• In other words, you're fired. Hey, I'm just kidding.

"Use Commas after Introductory Subordinate Clauses" was written by Joe Moxley.

To avoid confusion, use a comma after an introductory subordinate clause or phrase:

• Because the costs of conducting research continue to increase, we need to raise our rates.
• As the shrimp boats trawl, sea grass can collect on the trap door, allowing shrimp to escape.
• According to the professor, rich women are more likely to have caesarean sections than poor women.

"Use Commas around Nonrestrictive Parenthetical Elements" was written by Joe Moxley.

You should limit the number of times that you interrupt the flow of a sentence by placing modifying words between the subject and its verb. When you do introduce such appositives, participial phrases, or adjective phrases or clauses, you must determine whether the modifiers are restrictive or nonrestrictive. Essentially, restrictive modifiers add information that is essential to the meaning of the sentence, whereas nonrestrictive modifiers add information that is not essential. The best way to determine whether a modifier is restrictive or nonrestrictive is to see if taking it out changes the meaning of the sentence.

"Use Commas Before Nonrestrictive Adverbial Phrases" was written by Joe Moxley.

At the end of your sentence, you need to be especially careful about where you place your commas. In particular, you need to question whether the modifying words are restrictive or nonrestrictive. For instance, suppose you received a memo from your writing instructor that said,

• You should revise the essay, as I suggested.

"Use Commas to Join Two or More Independent Clauses" was written by Joe Moxley.

In most instances, place a comma between two sentences that are joined with a coordinating conjunction--and, but, or, for, nor, so, yet:

• She was not sure if she had the necessary mathematical abilities to be an engineer, so she pursued a graduate degree in history.
• He was surrounded by fifty people, yet he felt all alone.