A mind map is a database for tracking things when you don't know what is going to be tracked and/or how they are going to be related. You start with some central interest and then add pieces that relate. Good mapping software allows you to link relationships between distant relationships, associate minor bits of data, and easily change relationships between nodes.

I once started a job supporting several pieces of software on several servers in a new environment. I took disparate notes on this and that, but it would have been easy to lose specific pieces. So, I created a mind map of (Company Name), created nodes for server names and softwares. Then, I started filling in things for access information, credentials, installed software, useful scripts, etc. Eventually, I got a map of the whole system of a dozen servers, installed software, how they worked (and didn't), etc. I became the go-to guy for those systems because I knew them so well.