A comprehensive guide that documents all elements of a company’s brand identity and demonstrates how they’re used to ensure consistency and clarity throughout the organization.
Here's an analogy.
A brand guide is like an instruction manual. Its level of detail can vary based on the need and sophistication of the marketing apparatus, ranging from a 1-page quick reference guide to a 100+ page corporate brand standards guide.
Why does it matter?
Brand guides enable organizations to consistently express the values of the brand identity across many touchpoints, helping people shape a clear image of the company.
How does it apply?
Because the primary brand touchpoint for digital products is the product itself, the rules established in the guide should be considered in the product design style guide. For consumer-facing products the brand guide and product style guide are often synonymous (e.g., Airbnb). For enterprise products, it’s common to have a marketing brand guide and a product style guide with subtle adjustments to enhance usability.