what is a Brand Guidelines document ? I don't think it is necessary for my brand.
To put it in simple terms, a detailed document which spells out the a-z about your brand is what we call Brand Guidelines. A brand guideline explains how the brand will be showcased - online and offline as well. It gives a clear picture of what the brand does, who they cater to, what they stand for along with technical details. In the long run it even helps in marketing, maintaining the brand image and increases brand recognition.
So, you can either spend your time explaining about your brand or have a document ready to share whenever needed.
(Just saying, we'd choose option 1!)