Worried about Security, How is Coupons.com Tracking Me

I'm worried about my computer security. I've recently learned about printing online coupons. I know that you can print 1-2 coupons per computer, but as many coupons per printer or per IP address as long as you use a different PC. (I'm using latest verisions of Windows 8 and Firefox)

So how is this website and other coupons sites tracking me. Is it some kind of malware or spyware?
IDK its supposed to be a free legit thing but it's worrying me security wise.

FYI, I'm not trying to alter the coupons or doing anything illegal. Just would like to know what the deal is to protect my privacy. I already know that they sell your info to 3rd party companies so you shouldn't use your real name or birth date. Or must i sacrifice my privacy in order to save a buck?