mithrj, welcome to Apple Discussions.
Read the definition of "cookies" here:
http://en.wikipedia.org/wiki/HTTP_cookie
Cookies are necessary to view & use many sites. However, as explained in the above link, your web usage can be tracked.
I think you mean Firefox browser. I don't believe either browser is unsafe. I use Firefox because it has some features that Safari doesn't have.
Cheers, Tom