People don't read interfaces; they scan them for the word that matches what they want to do. Every label, button and message is either helping them find it or getting in the way. That makes interface writing one of the highest-leverage parts of design, and one of the most often left until last.
We write the words while we design the screens, because changing a word often changes the layout, and sometimes the feature.
Name things for what they do
A button should say what will happen: "Save entry", "Export backup", "Delete recording". Generic labels like "OK", "Submit" or "Continue" make people read the surrounding text to work out what they're agreeing to. For anything destructive, the button should name the thing being destroyed, so there's no doubt.
Use the user's words, not the team's
Every team builds up internal vocabulary: the names of systems, database tables and features in planning documents. None of it belongs in the interface. If people call it a "list", it's a list, even if the code calls it a collection. We test labels by asking whether someone who's never seen the product could say what each one does.
An error message is a conversation with someone who's already having a bad moment.
Write errors that help
A good error message says what happened, in plain words, and what to do next. "Something went wrong" does neither. "Couldn't connect to the App Store. Check your internet connection and try again" does both. Never blame the person, and never show an error code without a sentence beside it.
The best error message is the one that never appears, because the design prevented the mistake. Writing the error often reveals that the interface should have stopped the problem earlier.
Design the empty states
The first time someone opens a list, it's empty. That moment is an opportunity: a short sentence saying what will appear here and how to add the first item. An empty screen with no words looks broken.
Be honest, even when it's awkward
Interfaces are full of moments where the truth is inconvenient: a feature isn't available on this device, a backup can't be recovered without its passphrase, a subscription renews automatically. Saying so plainly, at the moment it matters, builds more trust than any amount of reassuring marketing copy.
Keep a consistent voice
We keep a short list of rules for each product: how we refer to the user, which words we use for key actions, how formal we are, whether we use contractions. It's usually a single page. It means two screens written months apart still sound like the same product.
Cut, then cut again
Most interface copy can lose a third of its words and get clearer. We write a first version, then remove anything the reader doesn't need to act. What remains is usually short, specific and easy to scan, which is exactly what interface writing should be.
Interface copy is part of our product design services. Read more in the journal.