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PUNCTUATION: CONSTRUCTING SENTENCES

Independent Clauses

A phrase that contains both a noun and a verb and can stand alone as a sentence.

Internal Comma

A comma contained within a clause, as opposed to a comma that appears before or after the clause.

Nonessential Element

A word, phrase, or clause that modifies but does not limit or change the essential meaning of a sentence.

Transitional Words or Phrases

Words or phrases that link independent clauses. Common transitional words and phrases include:

• accordingly
• afterwards
• again
• besides
• consequently
• doubtless
• eventually
• evidently
• furthermore
• however
• moreover
• nevertheless
• otherwise
• perhaps
• therefore
• for example
• for instance
• in addition

RULES

Pay attention to the way the following sentences are constructed; each sentence illustrates the rule it describes.

Semicolon or Comma

• Use a comma to separate two independent clauses that are joined together by and, but, or, for, nor, yet or so; if those words are omitted, use a semicolon. 
• The exception: use a semicolon if one or both clauses contain an internal comma (that is, a comma within the clause itself) where a misreading may occur if a comma is used. 

Dash

• Use a dash instead of a comma if you want to set off a nonessential element that needs special emphasis—but use it sparingly and for deliberate effect.
• If a nonessential element contains an internal comma—again, a comma within the element itself—use dashes instead of commas to set the element off. 

Parentheses

• Use parentheses to set off explanatory material (words that provide additional explanation or information) that is not necessary to the meaning of the sentence. 
• If you want to set off a nonessential element (words, phrases, or clauses that are not necessary to the structure or meaning of a sentence) but dashes would provide too much emphasis, and commas might be confusing or inappropriate, use parentheses. 

Colon or Semicolon

• With independent clauses, use a colon if the second clause explains the first: the second clause illustrates or provides specific information about the first clause.
• If the second clause does not explain the first clause, use a semicolon; using a colon in the sentence you are now reading would be wrong.
• Use a semicolon if the clauses are linked by transitional words or phrases; for example, phrases like however, besides, therefore, for example, for instance, and in addition are all transitional.
• If you’re unsure whether to use a colon or semicolon, your best bet would be to treat each clause as a separate sentence and use a period after each one.

Although this guide has been designed to address common punctuation problems, it is by no means exhaustive. If your specific concerns have not been addressed we encourage you to ask a tutor, check a reference manual, or see your professor.