When people ask me what a mind map is, I often give them 2 ways for looking at them.
The first defines mind mapping as a visual format that uses words, colours and images to represent information in a radial format starting in the centre and radiating outward using branches with related information.
Sounds like a mouth full… so I often also tell people that mind maps are ways to look at information differently. This different view allows the user to get different perspectives that gives them better insight, more clarity, peace of mind, understanding.
It is important to know that mind mapping is formalized by Tony Buzan. He is not the first person who created the mind mapping structure of working. Mind mapping structures were used by many people in history. Many smart people used it (and probably also many people who are not that famous).
Tony Buzan did create the system and gave it a name. I am sure that when you look back at the way you are taking notes, you used a similar way of working. The reason this probably happened to you before is because mind mapping comes very natural to us and our brains. The structure of mind maps is something that you see in nature a lot.