A “manual of style and usage” is a reference guide that provides rules and guidelines for writing and editing, covering aspects like grammar, punctuation, capitalisation, spelling, and formatting, aiming for consistency and clarity.

Style guides, also known as manuals of style and usage, are essential tools for ensuring consistency and clarity in writing and design, particularly across various industries and disciplines. They provide standardised rules for grammar, punctuation, formatting, citation, and other aspects of writing, helping writers and editors maintain a consistent style and tone.

I can think of two: The Elements of Style and Style Manual for Authors, Editors, and Printers (Australia).

I have recently stumbled upon The Chicago Manual of Style, 16th Edition, which is a style guide for American English published since 1906 by the University of Chicago Press

Why are style guides important?

• Consistency: Style guides ensure that all documents within a specific organisation, industry, or publication adhere to a consistent style, making them easier to read and understand.
• Clarity: By following established rules, style guides help writers avoid ambiguity and ensure that their message is clear and concise.
• Professionalism: Adhering to a style guide demonstrates professionalism and attention to detail, enhancing the credibility of the written work.
• Standardisation: Style guides provide a framework for writing and design, making it easier for different people to work together on the same project.
• Facilitating Communication: They help ensure that all content produced by an organisation or industry is consistent in its style, tone, and format, making it easier for the audience to understand the message.