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Although punctuation marks are small, punctuation takes on significant tasks: separating ideas, relating ideas to one another, clarifying meanings, and indicating changes from one voice to another. Without proper punctuation, readers can get confused and frustrated rather quickly. The following is a brief guide to all the puncutation types you will encounter in English and activities designed to give you practice with each of them.

Sentence Punctuation

In formal and semi-formal English writing, the sentence is the smallest complete textual unit. Aside from titles, anything less than a sentence (lacking an explicit or implicit noun or an explicit or implicit verb) is not acceptable. Most sentences in English end with periods (.), while question sentences end with question marks (?), and sentences indicating very strong emotions or voice end with exclamation marks (!):

  • Doris is working in accounting these days.
  • (You) Bring these papers to the notary.
  • (Management class begins at) 9:30 in the morning.
  • What’s the minimum page length for the final paper?
  • I won a full scholarship!

Questions and exclamations tend to be shorter than other sentences. Although there are no hard and fast rules to follow for sentence length, it is a good idea to keep them from becoming “run-on” sentences. If you do not limit the length, you risk confusing your audience. If a sentence you have written is getting overly long (which is probably the case if there are a lot of other punctuation marks in the sentence, or a lot of information with no punctuation at all), break it down into smaller idea units and insert periods for each:

Without Correct Punctuation

Chiyoko is doing the presentation tomorrow, it will cover Reconstruction following the American Civil War, there were so many topics that we covered in the Civil War chapter that I don’t know how she was able to choose just one, and the presentation has to be less than twenty minutes!

With Correct Punctuation

Chiyoko is doing the presentation tomorrow. It will cover Reconstruction following the American Civil War. There were so many topics that we covered in the Civil War chapter that I don’t know how she was able to choose just one. The presentation has to be less than twenty minutes!


Commas are perhaps the second most important punctuation mark to master, after periods. They are used to separate pieces of written text that are not adequate as full sentences by themselves. These pieces can be introductory words and phrases, dependent clauses, adjectives, or items in a list:

  • Last year, I did not have a driver’s license.
  • Sanjay, your work this quarter has been outstanding.
  • The test, a series of one hundred true-false questions, will be administered on the fifteenth of the month.
  • That sticky, smelly, yellow substance coming out of the wall might be a health hazard.
  • You will need to order cement bags, lumber, nails, nuts, bolts, screws, and glue.

Commas are also used for independent clauses that could grammatically stand as independent sentences, but are too short for academic or professional writing to be sentences on their own and are separated by a conjunction (for, and, nor, but, or, yet, so):

  • The project was tedious, but the district supervisor said it was vital.

Commas are also used to separate quoted material from text you have written yourself:

  • Phillip announced to the audience, “I want you to begin your research as soon as you leave the meeting.”

Finally, commas are used in the American style of writing calendar dates, and before a series of three digits in longer numbers (excluding years and decimals):

  • The national debt was calculated to be $9,571,475,766,176.63 at 5:52 p.m. on August 6, 2008.

Quick Guide to Commas

1. Use commas to separate independent clauses when they are joined by any of these seven coordinating conjunctions: and, but, for, or, nor, so, yet.

2. Use commas after introductory a) clauses, b) phrases, or c) words that come before the main clause.

3. Use a pair of commas in the middle of a sentence to set off clauses, phrases, and words that are not essential to the meaning of the sentence. Use one comma before to indicate the beginning of the pause and one at the end to indicate the end of the pause.

4. Do not use commas to set off essential elements of the sentence, such as clauses beginning with that (relative clauses). That clauses after nouns are always essential. That clauses following a verb expressing mental action are always essential.

5. Use commas to separate three or more words, phrases, or clauses written in a series.

6. Use commas to separate two or more coordinate adjectives that describe the same noun. Be sure never to add an extra comma between the final adjective and the noun itself or to use commas with non-coordinate adjectives.

7. Use a comma near the end of a sentence to separate contrasted coordinate elements or to indicate a distinct pause or shift.

8. Use commas to set off phrases at the end of the sentence that refer back to the beginning or middle of the sentence. Such phrases are free modifiers that can be placed anywhere in the sentence without causing confusion.

9. Use commas to set off all geographical names, items in dates (except the month and day), addresses (except the street number and name), and titles in names.

10. Use a comma to shift between the main discourse and a quotation.

11. Use commas wherever necessary to prevent possible confusion or misreading.