Period Punctuation Rules and Examples

The period [.] is the most common punctuation mark in the English Language. Also called the full stop, its use is universal and makes clear to a reader that they have reached the end of a sentence. 

Even though its use is easy to understand, its placement can sometimes be confusing. This is especially true when it’s used with parentheses and quotations. Let’s look at period punctuation rules and how to use them to clear up any confusion. 

What is a Period?

A period is the most commonly used punctuation mark in the English language. Also called a full stop in British English, it looks like a small dot and is used to designate the end of a sentence that issues a statement or command. 

In reading, its use introduces a significant pause to indicate a period is present to the listener. It can be used to show a word has been shortened, or that information has been removed, and it also has some other particular uses in math and technology. 

Period Punctuation Rules and How to Use Them

Although the use of a period is reasonably straightforward, it shows up in places other than the end of sentences. A period can also show up in ways that indicate the tone of a written piece to determine instruction or indirect questioning. Take a look at how you can use it to help clarify and define what you want your audience to understand. 

Does a Period Go Outside or Inside Parentheses?

Many people are confused about where the period goes when parentheses are used. Whether it is placed inside or outside the parentheses depends on whether the parenthetical is a complete, independent sentence. 

If the parenthetical is a complete sentence, the period goes inside the parenthesis. 

For Example:

  • I swear the dog thinks she’s human. (She sleeps with her head on the pillow and sits with only her butt in the chair.) She makes us laugh daily with her antics. 

If the parenthetical is nested within another, complete sentence, the period goes on the outside of the parenthesis. 

For Example:

  • I swear this dog thinks she’s human and makes us laugh daily at her antics (especially when she sits her butt in a chair). 

Does a Period Go Inside or Outside Quotation Marks?

The use of periods with quotation marks in a closing sentence isn’t as complicated as their use with parentheses. A period (or any punctuation mark) always goes inside the closing quotation mark at the end of a sentence.

For example:

  • My mother always used to warn us, “be careful what you wish for; it might not be what you thought.”

Use a Period to End a Sentence

The most common way to use a period is at the end of a sentence. It is one of three punctuation marks used to end sentences but is used at the end of a declarative or imperative sentence instead of question or exclamatory sentences. 

These sentences state or tell something.

For Example:

  • I want pizza for dinner tonight. 
  • Order us a pizza for dinner tonight. 
  • The pizza arrived five minutes ago. 

Use a Period to Ask an Indirect Question

An indirect question is a question that is said as a statement rather than asked in order to omit the question mark and use a period instead. 

For Example:

  • What is she doing tonight after school? Vs. I wonder what she’s doing tonight after school.
  • The question remains, who supports this bill? Vs. The question remained whether anyone supported the bill. 

Use a Period to Indicate an Omission

Periods also indicate an omission of letters from a word (called abbreviations) or information from a sentence. Periods shorten titles before a formal name, such as Mister to Mr. 

Latin abbreviations such as etc., i.e., and et al. are used to highlight that there is more information that could be given within the sentence that has been left out. An ellipsis (more on that below) is used to indicate the purposeful removal of part of a direct quote. 

For Example:

  • Mr. Smith was taking the dog on a hike. 
  • He carried with him water, a small bowl, a leash, etc., which was helpful for the hot day. 
  • The book’s authors listing Maggie Smith, John Cane, et al., let me know I would be sifting through at least three authors’ opinions on the subject. 

What Are Three Periods in a Row Called?

An ellipsis designates an omission of a direct quote or can represent a pause or hesitation in speech and dialog. It is characterized by three periods in a row […]. To learn more about ellipsis use, read our article What is an Ellipsis and How to Use It. 

For Example:

  • I tell you today; that you need to speak up…and represent all the people who voted for you. 
  • She nervously asked, “but what if…what if he doesn’t respond?”

Use Period for Abbreviations and Initials

As mentioned, abbreviations are a form of omission, and periods help indicate the location of missing letters when abbreviations are used. Abbreviations are tricky as they vary from case to case and, in British English, may be left out altogether in certain circumstances. For example, we shortened Doctor to Dr. in American English, but in British English, they leave it as Dr sans period. 

Keep in mind that if a sentence ends in an abbreviation, you do not add a second period. The period at the end of an abbreviation is sufficient. Take a look at a few examples of abbreviations and initials when used with periods.

Formal Titles

Formal titles are often abbreviated to avoid spelling out the entirety of the formality. These are well-recognized and accepted. 

For Example:

  • Mister or Missus: Mr. or Mrs. 
  • Lieutenant: Lt. 
  • Representative: Rep.
  • Bachelor of Science: B.S. 
  • Doctor of Philosophy: Ph.D.

Locations

Many geographical or man-made locations are abbreviated, as are some countries. 

  • Mountain: mtn. 
  • Road: rd. 
  • Street: st. 
  • Estuary: est. 
  • United Kingdom: U.K. 
  • United States of America: U.S.A

Name Disclosure

In some cases, a person may want to keep part of their name from being disclosed. In this case, periods would separate initials from the rest of the proper name. 

For Example:

  • A.A. Milne
  • J.R.R. Tolkein

Periods and Units of Time

Specific time periods, such as days and months, also have specific abbreviations that are widely recognized. The time of day is widely abbreviated since the formal name is such a mouthful and not well recognized in writing or speech. 

For Example:

  • Monday / Tuesday / Wednesday: Mon., Tues., Weds.
  • January / February / March: Jan., Feb., Mar. 
  • Ante Meridiem: A.M. 
  • Post Meridiem: P. M. 

Units of Measurement

Non-Metric Units of Measurement use periods in their abbreviation. Metric units do not. 

For Example: 

  • Inches: in. 
  • Pounds: lbs. 
  • Foot: ft. 

Latin Abbreviations

As mentioned above, Latin abbreviations commonly found in English writing always use periods. 

For Example:

  • Id est (that is)  : i.e.
  • Et cetera (and so forth) : etc. 
  • Exempli gratia (for example) : e.g.

Other Uses of Period

Periods are used in more than just writing situations; they are used as placeholders and are also depended upon for technology as well. Take a look at their importance in both math and technology. 

How Can You Use a Period in Math?

In mathematics, a period called a decimal point is an acceptable symbol for use as a decimal separator. A decimal separator is a symbol used to separate the integer from the fractional part of a number when written in decimal form. For example: 26.52

It can also be used as a digit group separator. In this instance, it is used in conjunction with a decimal comma. For example: 10.000,00 OR 10,000.00

How Are Periods Used in URLs?

A period is an integral part of a URL to designate website location. In this instance, it is not used as a punctuation mark but rather as a technological language that defines the database location of the information you are seeking. For example: Grammarist.com

It is important to note that a sentence that ends in a URL also includes a period at the end. For example: For great grammar support, visit Grammarist.com. 

How to Use a Period

A period directly follows the last letter of the last word of a sentence. Do not place an extra space between the word and the period.

DO: I am going for a walk. 

DON’T: I am going for a walk . 

Always place one single space after a period before beginning a new sentence. This space designates the start of the first word of a new sentence. 

DO: I am going for a walk. The day is perfect for it. 

DON’T: I am going for a walk.The day is perfect for it. 

DON’T: I am going for a walk.  The day is perfect for it. 

Why is the Period Important?

The use of a period indicates the end of a complete thought. Without its use at the end of a sentence, these thoughts will blend together and confuse the speaker or reader. When this happens, it is called a run-on sentence and is a very basic grammatical mistake. 

Without periods abbreviations would be random letters placed together. Their use allows the reader to know they are a shortened form of a longer word. 

Without their use in math and technology, you would not be able to find the site you are looking for or determine what the numbers actually represent. 

Let’s Review

The period is the most common punctuation mark in the English language and serves many purposes. Its most important job is to allow a reader or speaker to know that a sentence has ended and a complete thought is finished. 

It also indicates omissions of letters or words concerning abbreviations and quotes. Plus, it also serves as a placeholder in math and technology. 

Overall it is a vital mark to learn to make your writing clear and concise.