When do you use footnotes?

Do you use them to cite references? Are they simply for adding little comments? Or do you also use them for making connections with other notes?

My reason for asking this question: I wanted to make a connection between the note I was currently writing with another note that was unrelated yet had some connection. I felt that adding the link directly on the paragraph would be obtrusive (not sure if I’m using this word correctly), it made more sense to do it on a footnote because of how unrelated it was… thoughts?

if the title of my note doesnt fit inline with my text but I still want to reference it at a particular place as relevant to that text ill just put a footnote:

though in this example I probably could have fit it inline