[1] Typically a large number of customers search for a product/service or register as page view on a referring page which is linked to the e-commerce site by a banner ad, ad network or conventional link.
The metric used to describe this ratio is the click-through rate (CTR) and represents the top level of the funnel.
Typical banner and advertising click-through rates are 0.02% in late 2010 and have decreased over the past three years.
The process of understanding which creative material brings the highest click-through rate is known as ad optimization.
Adding the product to the shopping cart, registering or filling in contact details and payment all further reduce the numbers step-by-step cumulatively along the funnel.