This week's episode sees Aleks Krotoski examine the ways in which online businesses such as Google and YouTube have used the internet to make money from services that are apparently free. She talks to leading figures in the world of e-commerce, including Jeff Bezos, founder of Amazon, and Reed Hastings from movie rental company Netflix, and explains how the technological possibilities of the world wide web have enabled companies to tailor their advertising based on the information they gather about individual consumers' tastes.