Commas

1
Commas

• A Brief Guide to Correct Usage

2
The Definition of Comma

• A punctuation mark (,) used to indicate a
  separation of ideas or of elements within the
  structure of a sentence.

3
Instances where commas are necessary

• Lists within sentences
• Use a comma when listing more than three items
  in a sentence. Some editors say that a comma
  always appears before and and or in a
  sentence list. Other editors, including the APA
  for its publications, dictate that no comma
  should appear before conjunctions.
• Examples
• She gave him a book, a bell, a ruler, and a
  candle.
• He gave her a pencil, a pen, a photo, and an
  eraser.

4
Use a comma

• Before clarifying elements in a sentence
• When speaking, people pause before introducing
  examples of general categories. Commas help show
  this pause in writing.
• Examples
• She likes films with moral stories, such as High
  Noon.
• He bought several systems tools, including
  software.
• She has three cats, which does not mean that she
  hates dogs.

5
Use a comma

• After introductory and qualifying phrases
• When speaking, people pause after introducing
  information about time and place. Commas help
  show this pause in writing.
• Examples
• Before the meeting, we read the memo.
• When a paper is due, I experience anxiety, and
  then, unfortunately, I procrastinate.
• He ate more candy, of course, and he became ill.

6
Use a comma

• Between two related clauses separated by a
  conjunction
• Examples
• Income was up, but expenses were as well.
• The weather was clear, so we went hiking.
• She wrote the book, and then she wrote the
  screenplay.

7
Use commas here, too

• Dates, places, and numerals
• Examples
• Burlington, VT
• Washington, DC
• January 1, 2006 (no comma in European and U.S.
  military date usage 1 January 2006)
• 2,000
• 10,000