Growth Hacking is a way to make your marketing campaign go viral without your paying for it. For example, affiliate programs and promo codes allow your customers to promote your business for your without paying extra, aside from commissions of course.
Hotmail included a footer for new users to sign up causing every email sent out to be an advertisement.
Get press by creating a story around your company that writers would love to publish and their readers would love to share.
You can read more about that in this book...
