A style guide is a set of standards for the writing, formatting, and design of documents. A book-length style guide is often called a style manual or a manual of style (MoS or MOS). A short style guide, typically ranging from several to several dozen pages, is often called a style sheet. The standards documented in a style guide are applicable either for general use, or prescribed use for an individual publication, particular organization, or specific field.
A style guide establishes standard style requirements to improve communication by ensuring consistency within and across documents. They may require certain best practices in writing style, usage, language composition, visual composition, orthography, and typography by setting standards of usage in areas such as punctuation, capitalization, citing sources, formatting of numbers and dates, table appearance and other areas. For academic and technical documents, a guide may also enforce the best practice in ethics (such as authorship, research ethics, and disclosure) and compliance (technical and regulatory). For translations, a style guide may even be used to enforce consistent grammar, tones, and localization decisions such as units of measure.
Style guides are specialized in a variety of ways, from the general use of a broad public audience, to a wide variety of specialized uses (such as for students and scholars of various academic disciplines, medicine, journalism, the law, government, business, and specific industries). The term house style refers to the conventions defined by the style guide of a particular publisher or other organization.
Style guides vary widely scope and size. Writers working in many large industries or professional sectors reference a specific style guide, written for their usage in specialized documents within their fields. For the most part, these guides are relevant and useful for peer-to-peer specialist documentation or to help writers working in specific industries or sectors communicate highly technical information in scholarly articles or industry white papers.
Professional style guides of different countries can be referenced for authoritative advice on their respective language(s), such as the New Oxford Style Manual from Oxford University Press, UK; and The Chicago Manual of Style from the University of Chicago Press, US; both Australia and Canada have style guides – available online – created by their governments.
See also: List of style guides
The variety in scope and length is enabled by the cascading of one style over another, analogous to how styles cascade in web development and in desktop cascade over CSS styles.
In many cases, a project such as a book, journal, or monograph series typically has a short style sheet that cascades over the somewhat larger style guide of an organization such as a publishing company, whose specific content is usually called house style. Most house styles, in turn, cascade over an industry-wide or profession-wide style manual that is even more comprehensive. Examples of industry style guides include:
Finally, these reference works cascade over the orthographic norms of the language in use (for example, English orthography for English-language publications). This, of course, may be subject to national variety, such as British, American, Canadian, and Australian English.
Some style guides focus on specific topic areas such as graphic design, including typography. Website style guides cover a publication's visual and technical aspects as well as text.
Guides in specific scientific and technical fields may cover nomenclature to specify names or classifying labels that are clear, standardized, and ontologically sound (e.g., taxonomy, chemical nomenclature, and gene nomenclature).
Style guides that cover usage may suggest descriptive terms for people which avoid racism, sexism, homophobia, etc. Style guides increasingly incorporate accessibility conventions for audience members with visual, mobility, or other disabilities.
Since the rise of the digital age, websites have allowed for an expansion of style guide conventions that account for digital behavior such as screen reading (reading from a digitalized screen rather than a physical document). Screen reading requires web style guides to focus more intently on a user experience subjected to multichannel surfing. Though web style guides can also vary widely, they tend to prioritize similar values concerning brevity, terminology, syntax, tone, structure, typography, graphics, and errors.
Most style guides are revised periodically to accommodate changes in conventions and usage. The frequency of updating and the revision control are determined by the subject. For style manuals in reference-work format, new editions typically appear every 1 to 20 years. For example, the AP Stylebook is revised annually, and the Chicago, APA, and ASA manuals are in their 17th, 7th, and 6th editions, respectively, as of 2023.[update] Many house styles and individual project styles change more frequently, especially for new projects.