Here is a very important comma rule. Study it, and use it well in your writing.
Use a comma to separate nonessential or nonrestrictive clauses, participial
phrases, and appositives. A nonessential or nonrestrictive element adds
information that is not necessary to the sentence’s basic meaning.
• Nonessential or nonrestrictive clauses
The debate, which was attended by two hundred people, was exciting.
(The fact that two hundred people attended the debate is not
essential to the sentence’s basic meaning.)
ESSENTIAL CLAUSES: (Each underlined clause restricts the italicized
word that it modifies.)
The dress that Mom wore to the dinner last night was a gift from
A man who has confidence will go far.
• Nonessential or nonrestrictive participial phrases
My two buddies, posing for their high school reunion photo, have
worked for the government for the past thirty years. (The fact
that these two buddies are posing for their high school reunion
photo is not essential to the sentence’s meaning.)
ESSENTIAL PARTICIPIAL PHRASES: (Each underlined phrase restricts
the italicized word that it modifies.)
These cards left on the table belong to Gino.
The woman hailing the cab is my sister.
• Nonessential or nonrestrictive appositives
Stuart, my best friend, loves to laugh.
ESSENTIAL APPOSITIVE PHRASES: (Each underlined appositive phrase
restricts the italicized word that it modifies.)
Has your music teacher, Mrs. Brennan, given you the assignment?
The address, 1313 Mockingbird Lane, should ring a bell with televi-
viewers of that era..