Clauses and Punctuation Patterns

First things first...what is a CLAUSE?

A clause is a group of related words containing a subject and a verb.

What are the different clauses that can be used in a sentence?

Independent Clause
Dependent Clause
Essential Clause
Nonessential Clause

Independent Clauses

An independent clause is a clause that can stand alone as a sentence. It expresses a complete thought and has both a subject (who) and a verb (what/action). It usually ends with a period but can sometimes end with exclamation points or question marks.

Example: I enjoy visiting the Writing Center.
Example: Paul tutors science in the Learning Commons.

Dependent Clauses

A dependent clause is one that cannot stand alone as a complete sentence because it does not express a complete thought. Its a clause that implies that there is more to come further in the sentence and relies on that information from an independent clause to form a complete, logical thought. Dependent clauses have both a subject and a verb, so don't be fooled.

Depedent clauses are usually marked with dependent phrases or words, and these clauses can occur at the beginning OR the end of a sentence. For a list of these phrases and words, visit our Fragments and Dependent Clauses page.

Example: My mother is reading a book because my father is sleeping.
Example: Whenever I travel, I like to stay in fancy hotels.
Example: We struck up a great conversation with a person whom we met on the plane.
Example: She found it strange that they like to eat sushi.

Essential vs. Nonessential Clause

One of the trickiest distinctions in deciding whether commas are needed is the one between elements that are "essential" to understanding and those that are "nonessential."

Those technical words mean exactly what they say:

If the information that a phrase or clause adds is essential, the sentence can't do without it. An essential clause is necessary for the intended meaning of a sentence to be clear and is not offset with commas.
A nonessential phrase or clause can be lifted from a sentence with most of the meaning intact. If the sentence makes sense without the information and/or the clause is just additional information, it is a nonessential clause. These clauses ARE offset with commas.

Punctuation is an element of accuracy.

Sometimes, the presence or absence of commas is the only clue the reader has to the writer’s intended meaning:

The soccer player who scores goals is a crowd favorite.
The soccer player, who scores goals, is a crowd favorite.

Why are these two different in both meaning and punctuation?

The first sentence reads like a general statement that all soccer players who score goals will be popular. (The soccer player who scores goals is a crowd favorite.)
The second one seems to be referring to a specific player, that player "over there" whose popularity is not dependent on his goal-scoring. He just happens to score goals, which is why the information is nonessential. (The soccer player, who scores goals, is a crowd favorite.)

In the first version, the clause "who scores goals" is essential to the sentence. In the second sentence, that same phrase is not essential.

Here's a trick/rule of thumb: If the phrase or clause is not essential, then commas ARE essential. If the phrase or clause is essential, then we don't want those commas to butt in to the flow of the sentence.

Punctuation Patterns Chart

Here's a chart that provides a look at the patterns for punctuation the different clauses.

Independent Clause = green text
Dependent Clause = blue text
Nonessential Clause =red text
Essential Clause = purple text
--> = followed by

Components of the Sentence	Punctuation Patterns	Examples
Independent Clause	Independent Clause.	I went to the store.
Two Independent Clauses	Independent Clause, conjunction Independent Clause. OR Independent Clause; Independent Clause. OR Independent Clause; adverb, Independent Clause.	I went to the store, but I did not get everything on the list. OR I went to the store; I did not get everything on the list. OR I was in a rush at the store; therefore, I did not get everything on the list.
Dependent Clause --> an Independent Clause	Dependent Clause, Independent Clause.	Because I did not get everything on the list, I need to go to the store again.
Independent Clause --> a Dependent Clause	Independent Clause Dependent Clause.	I had to return to the store because I did not buy everything on the list.
First Part of an Independent Clause--> Nonessential Clause and the rest of the Independent Clause	First Part of an Independent Clause, Nonessential Clause, rest of the Independent Clause.	I went to the store, which is down the street from me, to purchase my groceries.
First Part of an Independent Clause --> Essential Clause and the rest of the Independent Clause	First Part of an Independent Clause Essential Clause rest of the Independent Clause.	I went to the store down the street to purchase my groceries.