Brand guidelines are standards you set for how you want your brand to be presented. This can help provide a consistent look and feel and is essential in controlling your image and how you come across.
In this case, I created them for my elements app. This allowed me to set rules for colour, sizing, typography, etc. This way, if someone else was to work on this app, they would know how they should design it and what they should avoid.
Here is a PDF of my brand guidelines:
I enjoyed doing this as it allowed me to ensure my app and brand were consistent in terms of colour, sizing, etc. I kept it simple, to the point, and clear. This makes it easy to understand if someone was to read this to work on my app.