March 21, 2018


What is a period?

A period is a punctuation mark that informs the reader that the author has completed a thought or idea. In the UK or when writing in the Queen’s English, a period is known as a full stop. A sentence is completed by a period followed by a single or double space. In the Chicago Manual of Style and APA (6th edition), one space is recommended between sentences.

Period Example:
Mickey Mouse and Donald Duck are characters created at Walt Disney Productions. Walt Disney Productions also created the character Goofy.

Other uses for the period

A period is often used with abbreviations, initials found in names, and reference abbreviations such as Volume (Vol.) and edition (ed.). Country names like the United States can be abbreviated to U.S. (although some styles only allow this change when the abbreviation is used as an adjective). State names, when abbreviated, do not require a period between capital letters, according to APA style. Uppercase abbreviations, such as American Broadcasting Company (ABC), do not require periods between capital letters.

Another common use of periods is the ellipsis. Ellipses are used to abbreviate or remove irrelevant information from quotes, comments, or an outside source’s original work. They can also be used in dialogue to indicate where a speaker has trailed off. Use of ellipses in quotations should be minimized, as they often distort the original author’s intended meaning or take a quotation out of context.

When to omit a period

It is also common to omit periods from chapter titles and other headings or subheadings. Periods are not required in ordered or unordered lists, but if a list item contains a period, then the sibling list items should also maintain a period at the end of each list item for consistency.

A period is not required at the end of a sentence if an abbreviation completes the sentence and contains a period. This is also true for URLs and email addresses that contain a trailing period.