Should you be able to remember the initial writing lesson back in early elementary school, it probably was: “a sentence starts with an uppercase, ends with a period and must make sense overall.”

While this statement remains completely true to this date, sentence structures employed by academics and professionals obviously look longer and more complex than those built on school’s benches.

In order to rhythm the flow of ideas in a clear, engaging and grammatically sound manner, punctuation—combining spacing and conventional signs—is definitely necessary.

But, albeit vital to disambiguate the meaning of sentences, punctuation abides by a set of rules which vary with language, location, register, and time. And, constantly evolving, certain aspects of punctuation are stylistic and are thus incumbent of authors and editors’ choice.

Comma

The comma indicates a soft pause in a sentence—a smaller break compared to a period that puts a definitive end. The comma is used in many contexts and languages, mainly to separate words, clauses, or ideas within a sentence.

Colon

The colon joins two independent clauses if the second amplifies or extends the first. The colon is often used after an independent clause to introduce a list, quote, explanation, conclusion, or amplification. The colon is sometimes described as being more effective than a comma, bearing less power to separate than the semicolon, and having more formality than the em dash.

Hyphen

The primary function of the hyphen—which is not a punctuation per se—is the formation of certain compound terms. The hyphen is also used for word division. The hyphen (-) is slightly narrower than the en dash (–) and even more so than the em dash (—). Never use a hyphen in place of an en dash or an em dash!

Dash

En dash

The en dash is used to represent a span or range of numbers, dates, or time. There should be no space between the en dash and the adjacent material. Depending on the context, the en dash is read as “to” or “through.” The en dash (–) is slightly wider than the hyphen (-) but narrower than the em dash (—). The typical computer keyboard lacks a dedicated key for the en dash, though most word processors provide its insertion under the “special character” insertion tab.

Em dash

The em dash is perhaps the most versatile punctuation mark. It is used to add emphasis or to insert definition or description almost anywhere in the sentence, thus can replace commas, parentheses, or colons. Notwithstanding its versatility, caution is required regarding its implementation. Its overuse loses impact and brings confusion. The em dash (—) is slightly wider than the en dash (–) and even more so than the hyphen (-). The typical computer keyboard lacks a dedicated key for the em dash, though most word processors provide its insertion under the “special character” insertion tab.

Parenthesis

The parentheses (always used in pairs) allows the insertion of an afterthought or explanation (a word, phrase, or sentence) into a passage that is grammatically complete without it. Therefore, when removing the material, the main sentence should not change and still remain sound. Parentheses give the reader permission to skip over the material.

Semicolon

The semicolon connects two independent clauses without using a conjunction like “and”. (Note: a clause always contains a subject and predicate; an independent clause can stand alone as a complete sentence.) Semicolons are also used to separate items in lists that contain internal punctuation. The semicolon is sometimes described as stronger than a comma but weaker than a period.

Period

The period, called a full stop in British English, is one of the first punctuation marks we learn about when we begin reading and writing: it shows that the sentence has finished.

Quotation marks

The quotation marks (always used in pairs) allow the insertion of a speech, a quotation, a phrase, or a word. Depending on the English version (British or American), quotation marks will either be ‘double’ or ‘single’. As a consequence, additional punctuation rules will ensue.

Double quotation marks

In American English, the double quotation marks (“x”) is the rule, but single quotation marks are applied for quotations within quotations. Moreover, additional punctuation should appear within the double quotation marks except when punctuation (exclamation point or question mark) emphasizes the writer’s sentence rather than the speaker’s quotation.

Simple quotation marks

In British English, the single quotation marks (‘x’) is the rule, but double quotation marks are applied for quotations within quotations. Moreover, additional punctuation should appear outside the single quotation marks except when the punctuation is part of the original quotation.