There was a time, not long ago, when eBook publishing was seen to be something for authors who were not successful in the mainstream press. However, the constant improvement of on screen reading technology has led to an increase in the popularity of eBooks. There are many ecommerce systems that allow authors to publish their books. Clickbank is one of the top ecommerce systems that will allow you to sell your eBooks. Clickbank is a unique online marketplace that allows people to sell all types of digital products. Clickbank boasts of having millions of users from all over the world.