This infographic illustrates some important factors such as Pay models, targeting capabilities, ad design, cost to pay, conversion, use for, keywords, likes, demo, Avg cost, demographics, internal/external destination URL, purchase intent and sales cycle.

With Google stepping up its efforts to penalize link networks and those who buy and sell links, and algorithms like Panda meant to reward sites with high-quality content, how important will backlinks be to Google's search algorithm in the future?

The boss of one of Europe's largest media companies has strongly criticised Google in an open letter printed in a German newspaper.