Punctuation is an important aspect of any written text. Good punctuation organises or divides the text to make meaning clearer; poor punctuation will make it difficult to understand.

2.1 General guidelines

Use common sense. Punctuation should help make written language clear to readers. If it does not, it should not be there. In line with most modern recommendations on this subject, we recommend light use of punctuation: as much as is necessary but no more.

2.1.1 Precedence

Be careful of using two or more punctuation marks in succession. Generally speaking, use the stronger or more necessary one. For example, question and exclamation marks are stronger than commas and full stops. However, quotation marks, brackets and ellipsis points are often used next to other punctuation marks. In the first of the two examples below, the question mark is used instead of the habitual comma and precedes the closing quotation marks; and in the second, a full stop is not needed because the exclamation mark already ends the sentence.

2.1.2 Punctuation and spacing

Punctuation marks in English – apart from dashes, ellipsis points, slashes and opening brackets – are always next to the preceding word, without a space.

Slashes are closed up to the preceding word and to the next word when they separate two single words.

When a slash separates two groups of words or a group of words from a single word, insert a space before and after the slash.

Full stops, question marks, exclamation marks, commas, colons and semicolons are always followed by a single space.

2.2 Full stops

Full stops, or points, present few problems. Use them for three main purposes: ending sentences that are not questions or exclamations, punctuating the numbers or letters used to list the elements of a summary, and separating the letters in some, but not all, abbreviations.

2.2.1 Indirect questions

Use a full stop, not a question mark, after an indirect question.

2.2.2 Items in lists

Use full stops after the numbers or letters that list the elements of a summary.

The individual items in vertical lists should only be followed by full stops when they form complete sentences (as above), not when they are simply nouns or noun phrases (as below).

Punctuate information contained in a list written in sentence form with a comma after each item in the list and the conjunction and or or before the last item, which is punctuated with a full stop.

If the list includes sentences punctuated with a full stop, the phrase introducing the list must end in a colon (as in the example) or a full stop.

2.2.3 Headings

Do not use full stops at the end of headings.

However, use full stops (not colons) in run-in heads, which should be italicised or written in boldface to make them stand out.

2.2.4 Sentences ending in abbreviations

If an abbreviation that takes a final point ends the sentence, this final point functions as the full stop.

In the case of questions and exclamations, however, finish the sentence with the final point of the abbreviation followed by a question mark or exclamation mark.

2.2.5 Footnotes and endnotes

End all footnotes and endnotes with a full stop.

2.3 Colons

Use colons mainly to introduce examples, explanations and specifications. In running text, a colon is preceded by a complete sentence; what follows it may or may not be a complete sentence, and may be a list or even a single word.

2.3.1 Common mistakes

Be careful with colons in the following situations.

i) Instead of a comma

Do not use a colon to substitute a comma.

ii) After a preposition

Do not use colons between a preposition and its complement.

iii) Two or more than one colon in a sentence

Never use more than one colon in a sentence.

Note, however, that you can use a semicolon and a colon together in the same sentence.

2.3.2 Other uses

i) Titles and subtitles

When you cite the name of a book which has both a title and a subtitle, separate the two with a colon. Do this even though no colon may appear on the cover or the title page of the book itself.

ii) Ratios

Ratios can be written with words (two to one) or with numbers and a colon (2:1).

2.4 Semicolons

2.4.1 Main functions

The semicolon is mainly used to join two complete sentences in a single sentence when (a) the two sentences are thought to be too closely related to be separated by a full stop and (b) there is no connecting word which would require a comma, such as and or but.

2.4.2 Alternatives to the semicolon

i) Full stop

A semicolon can generally be replaced by a full stop.

However, the semicolon suggests that the two shorter sentences are more closely related than two consecutive sentences.

ii) A connecting word

A semicolon can also be replaced by a suitable connecting word (and, or, but, while, yet) with a joining comma.

However, certain connecting words must be preceded by a semicolon or full stop. The most common are consequently, hence, however, meanwhile, nevertheless, therefore and thus.

2.4.3 Lists

Use semicolons to separate items in long or complex lists, or to make these items more conspicuous than they would be with commas.

2.5 Comas

As a general rule, commas can be used to list items in a series, to join sentences and to set off parenthetic or introductory phrases (for commas in lists in sentence form, see Section 2.2.2 Items in lists).

2.5.1 Listing items in a series

In a list containing a series of items, separate the items with commas. However, a comma should not precede the conjunction before the final item (in other words, write a, b and c and not a, b, and c). But if a comma would make the meaning clearer, use it – especially when one of the items in the list is already joined by and.

2.5.2 Joining sentences

When you join two complete sentences into a single sentence, you can use commas but follow them with a suitable connecting word: and, or, but, while or yet.

The comma is not required if the subject of the second part of the sentence is omitted or if the conjunction used is and or or.

2.5.3 Other uses of the comma

Separate a city from a state, province, region or country with a comma.

Do not use a comma between the month and the year.

In most numbers of one thousand or more, use commas between groups of three digits.

Exceptions are degree temperatures, years, addresses, page numbers and other uses of numbers for a non-quantifying purpose (see Section 5.2.2 Commas).

2.5.4 Misuse of the comma

Do not put a comma between the subject and the verb even if the subject is very long. Therefore, in the sentence below there is no comma between the words own (the end of the long subject) and are (the first word of the verb phrase).

2.6 Dashes

A dash is similar in appearance to a hyphen, but is longer and used differently. The most common version of the dash is the en dash. Use it with spaces to make a parenthetical reference.

Use it without spaces to express a connection or to indicate a date, time or number range.

Ranges can be expressed by a dash or by the words from and to (or between and and) but never by a combination of from (or between) and a dash.

2.7 Brackets

2.7.1 Round brackets

Round brackets are primarily used in four situations.

i) Secondary or marginal information

Use round brackets to indicate information that is secondary or marginal to the main idea of the sentence.

ii) Explanations or abbreviations of preceding information

Use round brackets to expand on or explain preceding information.

When a passage within round brackets is at the end of a sentence, of which it is only a part, place the full stop after the closing bracket. However, when the bracketed passage is a complete sentence, place the full stop before the opening bracket and then add a second full stop before the closing bracket.

iii) Options

Use round brackets to represent options.

iv) Enumerations in a body of text

Use round brackets to enclose numerals or letters in an enumeration in the body of a text. Use roman type rather than italics for the numerals and letters.

2.7.2 Square brackets

Square brackets are less common than round brackets. They are primarily used in three situations.

i) Clarifications within quoted text

Use square brackets to set off a clarification within quoted text.

ii) Optional or tentative text

Use square brackets to indicate text that is optional or still open to discussion. In the following example, the School of Education is responsible for implementing the project. What is optional or uncertain is whether the Office of External Relations will share that responsibility.

iii) Brackets within brackets

Use square brackets to indicate parenthetical elements that are already in round brackets.

2.8 Question marks

2.8.1 Direct questions

Place a question mark at the end of any sentence that is a direct question.

If the question is a direct quotation, repeating the speaker’s exact words, a question mark is still used.

2.8.2 Other types of question

i) Indirect questions

Do not use a question mark in an indirect question, in which the speaker’s exact words are not repeated. Use only a full stop, since the whole sentence is now a statement.

ii) Courtesy questions

If a request or instruction is put as a question for reasons of courtesy, do not use a question mark.

2.9 Quotation marks

Use quotation marks, also called inverted commas, to indicate direct quotations and definitions.

As in the examples above, punctuation should be placed according to the meaning: if it belongs to the quotation, it is quoted; otherwise, it is not.

Although there is a diversity of guidance in this respect, we recommend using double marks for a quotation and single marks for a quotation within a quotation.

Quotations of over four lines in length should be set off from the text as a block quotation, not enclosed in quotation marks, and single-spaced. Quoted matter within the block quotation is set off with double quotation marks; quotations within these quotations, with single quotation marks.

Single quotation marks can also help show the reader that a word or term is used in an unusual, colloquial or ironic way.

Also, use quotation marks for titles of chapters in books, articles in periodicals, and TV and radio programmes.

2.10 Exclamation marks

An exclamation mark is used at the end of a short phrase or a sentence that expresses very strong feeling. It is one way of adding emphasis and in our institutional context it may be used in public announcements of certain kinds, university relations and advertising.

However, exclamation marks are very rare in formal English, so use them sparingly. Finally, never use more than one exclamation mark in a row.

2.11 Apostrophes

In general, we use apostrophes to indicate possession or contracted forms.

2.11.1 Possessive forms of nouns

The possessive form of a singular noun is marked by an apostrophe followed by s.

This rule applies in most cases even with a name ending in s.

If a plural noun already ends in s, the apostrophe is used alone.

Note that the apostrophe is also used in expressions of time.

Degree titles should be written with an apostrophe followed by s.

But note the exception: doctoral degree, not doctor’s degree.

Do not use apostrophes to indicate a decade, a plural acronym or the plurals of figures.

2.11.2 Contractions

Use apostrophes for contractions (you’re for you are, don’t for do not, it’s for it is or it has), but note that contractions are far less common in formal texts than they are in informal writing.

2.12 Ellipsis points

Use ellipsis points with a space on either side to denote pauses. Use them at the end of a sentence without a space to indicate that the sentence has been left unfinished.

Use ellipsis points with square brackets to denote words missing from a direct quotation.

Do not use ellipsis points to indicate an incomplete list.