A brand guideline is a set of rules and guides of what to do and what not to do when it comes to a brand. Usually this consists of colour palettes, the fonts used and a list of rules, accompanied with examples of what is meant by these rules and restrictions. It can become quite elaborate or very simple, depending on how serious the overall image of a brand is taken.
Have you ever noticed that Nike, for instance, never uses their icon in reverse? This is just a simple way of showing how a design has to be restricted to represent the brand correctly.
These restrictions can range from the colours used in the logo itself or accompanying designs, the font used and even the font size, dimensions and colour. It can include restrictions regarding spacing of designs or even what parts of the branding is allowed to be used together.
This guideline will usually be given to your graphic design company to make sure they stay true to your brand image. This document can also be used internally to ensure that the company employees use the branding correctly when drafting documents, creating internal notices, etc.
This document can be printed as a hard copy or sent as an electronic file, which is usually the version that is used today. When you select a design company, it is very important for you to mention that you have a brand guideline which they will need to adhere to. It is very good to provide this beforehand and confirm if they can keep to the restrictions set out. If so you can also enter into an agreement to confirm receipt of set restrictions and create a clear understanding of the expectations going forward.
If your branding is important to you, take the time to choose a design team who will also take it seriously.