Editing Comma (section)

=== Parenthetical phrases ===
{{anchor|Parenthetical phrase}}
Commas are often used to enclose [[parenthesis (rhetoric)|parenthetical]] words and phrases within a sentence (i.e., information that is not essential to the meaning of the sentence). Such phrases are both preceded and followed by a comma, unless that would result in a doubling of punctuation marks or the parenthetical is at the start or end of the sentence. The following are examples of types of parenthetical phrases:
*Introductory phrase: ''Once upon a time, my father ate a muffin.''<ref>''Garner's Modern American Usage'', (Oxford: 2003, p. 655)</ref>
*Interjection: ''My father ate the muffin, gosh darn it!''
*Aside: ''My father, if you don't mind me telling you this, ate the muffin.''
*[[Apposition|Appositive]]: ''My father, a jaded and bitter man, ate the muffin.''
*Absolute phrase: ''My father, his eyes flashing with rage, ate the muffin.''
*Free modifier: ''My father, chewing with unbridled fury, ate the muffin.''
*Resumptive modifier: ''My father ate the muffin, a muffin which no man had yet chewed.''
*Summative modifier: ''My father ate the muffin, a feat which no man had attempted.''

The parenthesization of phrases may change the connotation, reducing or eliminating
[[ambiguity]]. In the following example, the thing in the first sentence that
is relaxing is the cool day, whereas in the second sentence, it is the walk since the introduction of commas makes "on a cool day" parenthetical:

:''They took a walk on a cool day that was relaxing.''

:''They took a walk, on a cool day, that was relaxing.''

As more phrases are introduced, ambiguity accumulates, but when commas separate
each phrase, the phrases clearly become modifiers of just one thing. In the
second sentence below, that thing is ''the walk'':

:''They took a walk in the park on a cool day that was relaxing.''

:''They took a walk, in the park, on a cool day, that was relaxing.''