Voice and tone

The voice

The interface speaks like a colleague who knows the product well and respects the reader's time.

• Calm. State what happened and what to do next. Save the exclamation mark for a real celebration, at most one per screen, and never on an error or an empty state.
• Knowledgeable. Say the specific thing: "Invoice sent", not "Done".
• On the reader's side. Write from their point of view and let the system take the blame: "Your computer appears offline", not "You went offline".

Politeness has a budget

• Use please only when you are genuinely inconveniencing the reader.
• Use sorry only for real harm or data loss.
• Use thank you only when the reader did something extra.
• Cut easy, simply and just. They judge the task instead of describing it, and the task is not easy for everyone.

Casing and punctuation

• Sentence case everywhere: buttons, labels, headings and body. Never all caps: it is hard to read, and screen readers handle it badly.
• Capitals mark proper names only. Write "fraud analysis", not "Fraud Analysis", unless it is a branded product name.
• No trailing punctuation on labels, buttons, headings or single-sentence strings. Use periods only in bodies of two or more sentences. No colon after a form label.
• Spell symbols as words. Write "then" instead of ">", because screen readers read symbols badly or skip them.
• Use the serial comma, "and" instead of "&", and never "and/or". Avoid semicolons and em dashes in product copy; split the sentence instead.
• Put user-provided content and file names in quotes, and UI element names in bold.

Do and don't