Style Guide

A style guide is a collection of rules for how something should look and sound. It determines, for example, whether a company addresses its customers informally or formally. It defines which shade of blue is used in the logo and which typeface appears on the website. Newspapers have had such rulebooks for over a hundred years, where they are often called an editorial style guide. The purpose is always the same: many different people should produce a result that looks as if it came from a single hand. You can think of a style guide as a brand’s house rules — not particularly exciting to read, but without it, chaos reigns.

Why brands insist on consistency

A brand is built through recognition. If every ad uses a different typeface, nobody remembers who sent it. Large companies spend millions to make sure their appearance looks the same everywhere. A style guide protects this investment by making deviations unlikely.

There’s also a practical reason: it saves discussions. Without a rulebook, every team argues anew about whether it’s spelled “e-mail” or “email.” Once the decision is written down, the question is settled. For a corporation with thousands of employees, this time savings adds up considerably.

A third point is reliability toward the audience. News sites regulate in their style guide how to handle names, numbers, and sensitive phrasing. Such guidelines are not a matter of taste. They ensure that readers can compare texts and don’t have to decipher a different logic in every article.

What such a rulebook actually contains

The visual part describes colors, fonts, spacing, and logo variants. Colors are not specified as “dark blue,” but as an exact numeric code. This way, a print shop in Hamburg can hit the same tone as a web designer in Berlin. Often it also specifies what you must not do: distort the logo, change the color, add elements.

The linguistic part governs tone and word choice. It states whether sentences should be short, whether technical terms are allowed, and which form of address applies. There are often word lists with preferred and discouraged terms. Some guides include example sentences in two columns: on the left the bad version, on the right the good one.

In connection with AI, the style guide takes on a new function. It can be given to a language model — that is, a program that formulates text — as an instruction. The model receives the rules together with the actual task and aligns its output accordingly. With very extensive rulebooks, however, this only works to a limited extent. The longer the specification, the more likely individual points fall by the wayside.

From the binder on the shelf to the machine directive

In the past, a style guide was a printed manual. Today it’s usually a webpage on the company network or a file in a design tool. Programs like Figma allow colors and fonts to be stored directly as reusable building blocks. This means the guide is not just described, but technically enforced.

In the news, the term currently appears mainly where editorial teams use AI. Major publishers have released their own rulebooks specifying what generated text may and may not be used for. The operators of the AI models themselves also work with such documents. OpenAI, for instance, publishes a Model Spec that describes how the system is supposed to behave.

A common misconception is that a style guide is purely cosmetic. In fact, it often contains legally relevant provisions, for instance regarding the labeling of advertising. Related, but not identical, is the design system: this provides ready-made components like buttons and forms, while the style guide describes the rules behind them. In practice, the two are increasingly merging.