Punctuation

Quick Reference

Key Principles

Scannability, clarity, and readability hold priority over rigid rules in unclear situations.

Single phrases don't wear punctuation unless they socialise to form a complete sentence.

Oxford commas make everything easier, clearer, and sexier.

Contractions speak volumes, and louder, when they are absent than when actually used.

Mark	Glyph	Rule
Apostrophe	'	Contractions, possessives (not possessive pronouns nor simple plurals).
Colon	:	Use to introduce lists. Use to introduce explanation. Don't use at the end of titles, subtitles, and headings.
Comma	,	Use to separate list items (Oxford comma). Use to set off nonessential phrases. Avoid unnecessary commas in UI.
Contraction	'	Use for conversational tone only. Consider clarity for ESL users. Avoid in critical safety instructions where full form adds emphasis.
Ellipse	… (…)	Only use in editorial content quotes: - to illustrate unfinished sentences or pauses in quoted person's speech - between parentheses to signal edited or incomplete quote Don't use in place of "etc." to mark incomplete list.
En Dash	–	Use for ranges of dates or numbers.
Em Dash	—	Use sparingly for abrupt changes or emphasis.
Exclamation Mark	!	Use very sparingly: - for critical alerts - for strong positive confirmations
Hyphen	-	Use for compound adjectives before nouns. Use for number ranges when space is too limited for en dash. Avoid prefix hyphenation except specific cases.
Period (Full Stop)	.	Use to end complete sentences. Omit in most UI elements (labels, buttons, short list items).
Question Mark	?	Only use to end a direct question.
Quotation Mark	"..." '...'	Use double (") by default; use single (') for quote within quote. Avoid in UI (short direct quotes if necessary). Don't use for titles or emphasis.
Semicolon	;	Use to combine related sentences (instead of using a conjunction). Use to separate long items in a series. Don't use to introduce a list.
Slash	/	Only use technically, for fractions, and in place of "per". Don't use as alternative for "or". Exception: "and/or" is allowed.

Periods (full stops)

Phrase < Sentence

A phrase is a group of words playing a specific role within a sentence that doesn't express a complete thought on its own, and doesn't contain both a subject and its corresponding verb.

A sentence is a group of words or phrases that assemble to express a complete thought, including a subject (someone or something that performs an action) and a predicate (what the subject is or does, usually including a verb).

Use periods normally when writing:

body text

UI text that forms a complete sentence

UI items that contain multiple complete sentences

Use periods for descriptive UI text with complete sentences like:

popovers

alerts

dialogs

overlays

Don't

Don't use periods in:

single-phrase UI text

multiple-phrase UI items without complete sentences

Don't

Don't use periods in the following UI components:

buttons, badges, and labels

single-line tooltips

lists with items that don't form complete sentences

headings

UI Tips & Tricks

Prioritise scannability in UI elements by omitting unnecessary periods.

Use periods to ensure clarity in longer instructional text.

Commas

Use commas to separate items in lists (use the Oxford/serial comma for clarity) and to set off nonessential clauses.

Avoid comma splices in short UI text: use semicolons or break text into separate sentences to facilitate readability and reduce ambiguity of commas joining independent clauses.

Oxford comma

Select voltage, current, and frequency.
Not: Select voltage, current and frequency.
The Oxford comma (the comma before "and" in a list) enhances clarity and prevents ambiguity.

Joining clauses

Do: The system is active; it is ready for use.
Do: The system is active. It is ready for use.
Don't: The system is active, it is ready for use.
Avoid comma splices. Use semicolons or separate sentences to join independent clauses.

Contractions

Contractions improve scannability in UI messages and help text when natural conversational tone is appropriate.

Avoid contractions in safety-critical instructions: use full form to add emphasis ("do not" instead of "don't").

General help and UI messages

Do: Don't forget to save your work before closing your session.
Don't: Do not forget to save your work before closing your session.
Clear and simple language. Avoid disturbing unnecessary use of the full form.

Safety emphasis

Do: Warning: do not exceed maximum load.
Don't: Warning: don't exceed maximum load.
The full negation form adds emphasis. Users might miss the instruction's importance with contractions.

Potential clarity issue

Do: What is the target voltage?
Don't: What's the target voltage?
Clear to all readers. "What's" could be potentially unclear (watts/what's) to less proficient English speakers.

Apostrophes

Use apostrophes for contractions and possessives.

Contractions

Do: It's important to back up your data.
Don't: Its important to back up your data.
The apostrophe in It's correctly indicates the contraction of It is.

Singular noun possessives

Do: The device's settings
Don't: The devices settings
The 's (apostrophe + s) is correctly used to show possession for the singular noun device.

Possessives of plural nouns ending in "s"

Do: The operators' systems must be updated by 2030.
Don't: The operators systems must be updated by 2030.
For the plural noun operators (already ending in s), the apostrophe is correctly placed after the existing s to indicate possession.

Avoid possessive apostrophes with plural nouns

When expressing possession for a plural noun, consider rephrasing the sentence to use the plural noun as an adjective, or to restructure the phrase, thereby often avoiding the need for a possessive apostrophe.
Instead of: "The companies' CEOs have released a common statement."
Better: The company CEOs have released a common statement.
Or: The CEOs of the companies have released a common statement.

Possessives of plural nouns NOT ending in "s"

Do: The children's toys are fun.
Don't: The childrens' toys are fun. or The childrens toys are fun.
For a plural noun that does not end in s (like children), possession is correctly shown by adding an 's (apostrophe + s).

Possessive pronouns

Do: The system is running at its optimal level.
Don't: The system is running at it's optimal level.
The possessive pronoun its is correctly used without an apostrophe. It's is the contraction for it is.

Common incorrect use of apostrophes for simple plurals

Do: The reports are ready.
Don't: The report's are ready.
Apostrophes are not used to form regular plurals of nouns.

Colons

Use colons to create a clear visual break and signal the introduction of related information:

lists

explanations

elaborations

Don't use colons at the end of headings.

Introducing lists

Do: The following parameters are required: - Voltage - Current - Resistance
Don't: The following parameters are required - Voltage - Current - Resistance
A colon is correctly used here to introduce the bulleted list that follows an introductory clause.

Integrated lists

Do: Required parameters include voltage, current, and resistance.
Don't: Required parameters include: voltage, current, and resistance.
No colon is used because the list flows naturally from the verb include.

Label-value pairs

Do: Status: active
Don't: Status - active
A colon is used to clearly separate the label from its value.

Semicolons

Use a semicolon rather than a comma to combine two sentences without a linking conjunction.

The workers council and the board reached an agreement; the strike ended immediately.

Use a semicolon in a series to separate items that are long, complex or include internal punctuation.

The company ping-pong team was constituted as follows: HR, 4 members, including 1 senior manager; Legal, 5 members, including 2 external consultants who've been working at the company for years; and IT, 2 members, including a semi-professional player.

Ampersands

In general, spell out the word And instead of using the ampersand (&) to improve readability and make scanning easier.
Don't use the ampersand after the Oxford comma in a list of three items or more, in body text, and email subject lines.
However, the & symbol can be used in elements where space is limited: headlines, column headers, table headers, navigation labels, and buttons.

Hyphens

Number ranges: avoid

Only ever use hyphen for number ranges when space is too limited to use en dash, and every pixel counts (table headers, labels, buttons, etc.)

220-240V

15-30 May

Compound modifiers: use before the associated noun

A compound modifier (also called a compound adjective) is a combination of two or more words compounded into an adjective.
Use hyphens in compound adjectives before the noun:

The high-voltage system is very sophisticated.

This is a well-known issue.

Do not hyphenate compound adjectives after the noun:

This system is a high voltage network.

This issue is well known.

Prefixes: it's half-complicated

In general, don't hyphenate common prefixes.

You need to reconnect your computer to a secure network.

But there are cool exceptions that demand hyphenation:

When the prefix's final vowel is also the initial of the following word, hyphenate to avoid the vowel touching itself:

Re-examine is correct.

Reexamine is wrong.

When the second word is capitalised, hyphenate:

The metric system is seen as un-American by someone, probably.

When the prefix is all-, full-, or half-, hyphenate:

half-life, full-stack, all-star

Use a hyphen when a figure follows mid-, pre-, post-, anti-, non-, or ex-:

I'm in my mid-40s

En Dashes

Use en dashes – for ranges

Use an en dash – for ranges.

June–August

50–100 kW

Em Dashes

Use em dashes — to mark emphasis or abrupt change

Use em dashes — very sparingly for emphasis or to mark an abrupt change in the narration.

The system was stable — or so we thought — until the power surge.

The results were conclusive — immediate action was required.

Don't combine a dash with a colon

Colons and em dashes are sometimes used in the same sentence, but they cannot be used at the same place.

First step: check the connections.

Start with the first step — check the connections.

Don't

First step:— check the connections.

Start with the first step —: check the connections.

Slashes

Slashes can be used in limited technical contexts: when replacing per, in fractions, and in abbreviations.

The city's population density is 1500p/km².

Input must be within a tolerance of 1/10th of the expected value.

The speed limit is 130 km/h.

Attention points

Avoid using slashes to combine words: prioritise or over a slash sign / to signal alternatives.

Only use / to replace or when absolutely necessary in small UI elements where space is very limited, like tags, table headers, and buttons.

Question Marks

Hi, Mark, my name is Quotation.
Now that we've got this incredibly funny joke out of our system, let's dive into it.

Only use question marks to end a direct question.

Do you know what a direct question is?

Don't use to end indirect questions.

I wonder if you really know what a direct question is, or if you're bluffing, Martoni.

Exclamation Marks

Unless they play a specific technical function, exclamation marks should be used very sparingly, and only for:

critical alerts

strong positive confirmations

Examples:

Attention: by clicking this button, you will definitely cause a city-wide power outage!

Congratulations: you've successfully ended the power outage caused by your colleague!

Quotation Marks

Only use the common English double "bla bla" or simple 'bla' quotation marks.

By default, use double quotation marks "…"

"I don't think he's bluffing", the protagonist replied.

Simple quotation marks '…'

Unless they play a specific technical function, simple quotation marks should only be used for quotes within quotes (aka quoteceptions).

"I know he said 'I don't think he's bluffing', we just watched the movie together!", she sighed.

Caution

Avoid using quotation marks in UI elements (short direct quotes if absolutely necessary).

Don't

Don't use quotation marks to indicate titles: use Title Case.

Don't

Don't use quotation marks for emphasis (use bold).

Use actual quotation marks, not backticks or apostrophes: just move your fingers a little bit upwards, it's good exercise (Vim is not an excuse; get over yourself!).