A mind map is a diagram used to visually organize information.
A mind map is hierarchical and shows relationships among pieces of the whole. It is often created around a single concept, drawn as an image in the center of a blank page, to which associated representations of ideas such as images, words and parts of words are added. Major ideas are connected directly to the central concept, and other ideas branch out from those.
Below, you will find some tools to create digital mind maps although you could freely draw yours on a sheet of paper.
https://www.mindmeister.com/es
