I have learned the concepts for solvable, supersolvable, and nilpotent groups and their associated properties. In particular, we have $$\{\mbox{nilpotent groups}\}\subset\{\mbox{supersolvable groups}\}\subset\{\mbox{solvable groups}\}$$ I know that the term "solvable" comes from Galois theory where there is a correspondence between the Galois group and the solvability by radicals. But how about "supersolvable" and "nilpotent"?
For "supersolvable", what makes it so special that we need to define such a term? Is there any special application of these groups that sets "solvable groups" apart?
For "nilpotent", it somehow sounds a strong property to me, e.g., it is a direct product of its Sylow subgroups when finite. But the name sounds a bit puzzling, this somewhat like the idea of homology?
PS: I am a researcher working in the field mainly related to finite group theory. I heard that these terms have some relation with Lie algebra, which I haven't learned. So I am hoping some gurus can lead my way:-)