From what I remeber from the books, ComStar is the group that owns and runs all communication. They basically listen to what everybody is saying to eachother and pull strings from behind the scences. The reason C-bills (ComStar Bills) are so widely used is because it is the only thing of common value, because worlds printed their own money. So C-bills printed by ComStar can be traded because you can send messages with it, and messages were required for a group of worlds to stay in contact so everybody used them as the medium of exchange. The only other way to send a message was to hand deliver it by dropships which takes week or months depending on how far you had to travel.
From the jade falcon books, ComStar actually helps to "delay" the clan invasion. I believe they make a deal with the clans that if they can hold them from some planet, the clans are not allowed to attack for a certain period of time or something. I would have to dig that trilogy out (amazing trilogy btw you should read it) but I remember a scene described at the end of the last book. The main character (a clanner from jade falcon) is getting overrun by ComStar mechs as they pop out of the ground like ants and force the jade falcons to retreat off planet. I do not describe it as well as the book but it basically is like a river of mechs just flowing out of the ground and running over the clan mechs as if they were nothing do to sheer numbers.
If you ever want to read the most epic books about the clans and how they worked you MUST read the jade falcon trillogy.
(SPOILER!!! DON'T READ THIS PART IF YOU INTEND TO READ THE BOOK) I belive the main charicter dies holding off 30+ mechs (and killing most of them) so that the jade falcon dropships can escape and his genitics get added to the vualt of jade falcon forever.
Edited by Twisted Power, 22 June 2012 - 07:00 PM.