Why is the Guideline important?

Imagine buying a new car without having the manual to know about the various function in the car. Even though if you do not use the manual every day, you know its somewhere and you can check it if need be. So also, is the brand guideline. It is needed to accurately identify and document the different brand elements of a company. This understanding helps in making great internal and external communications.
Also, it is important to note that the brand agency who developed the brand identities may no longer be around and it will be the duty of another agency to keep working on the brand. Omnicom’s Arnell Group, world-renowned brand strategy, marketing communications, and design firm who redesigned the Pepsi Logo closed their studio in 2013. It is crucial for brands to have and keep this record.
The brand guideline is the property of the brand owner, and it is needed as documentation and official representation of the brand elements. This can also be useful for future brand identity revisions. It is essential to know what the brand has documented and how to move on from there. For consistency sake, the guideline offers a central hub for all the users working with the brand to get the information needed. It is essential that the right shade of red is used across the media, irrespective of screen or country.
The availability of the brand guidelines also helps large organisation appear consistent across different touchpoints. Wherever the brand operates, the same message is passed. This also help both internal and external users working on the brand; they do not have to stress themselves working on how to communicate effectively, the brand guidelines are there to help them.