Viral Marketing is a really cool mechanism. Just imagine about it…, instead of spending an insane amount of money on newspaper ads, TV commercials, or banner ads – you spent nothing, and let your fans do all the work for you.
One of the fundamental equations of viral growth is,
k = e . i
where “e” is the efficiency of your loop and “i” is the average number of invites per user. “k” is the viral coefficient or the average number of additional users each new user brings in. If k >1, you get viral growth.