I’ve recently re-discovered the app MindNode, an app that helps diagram ideas and thoughts in a visual way.
Here’s an example of what a basic mind map structure looks like:

Just a simple diagram I generated about mind-mapping and why I use MindNode instead of other similar apps.

Maps can be used in a variety of ways of course. I have used mapping for
productivity, goals, notes, brainstorms, problem solving, book
summaries, task management, video summaries ( I take notes while
watching TED or podcasts). Here lately though, I have been using it to
map out plots and story ideas for the novels yet to be but on paper.
Here is a sneak peek of one of them:

Redacted of course! Can’t give it all away just yet.