Beacon is an advertising system developed by Facebook, a method by which Facebook exploits the commercial value of the data it gathers about its users. Beacon allows Facebook to share personal data with a number of online retail ‘partners’ – receiving the data gathered by those retailers in exchange. The Beacon system was originally intended to be to all intents and purposes a covert system, and an ‘opt out’ system – all Facebook users were intended to be included unless they found out about it and specifically asked not to be included. That in itself raises a lot of issues – the thorny issue of consent to start with – but it also demonstrates how these kinds of commercial alliances can be formed. Members of the alliance would quite naturally wish to be mutually supportive – and hence do their best to support each other to thedetriment or exclusion of competitors. This is just normal business practice – but if similar systems were extended onto search engines it is easy to see how conflicts of interest might result in unfair or misleading search results – and consequent manipulation of how people navigate the web. The reality behind Beacon was discovered before it came into action, and the privacy issues surrounding it raised such a furore that Facebook was forced to change it significantly it before it was implemented, making it opt-in rather than opt-out, amongst other things.The changes forced by users are revealing, in two particular ways. Firstly, it demonstrates why companies often keep the real reasons for their data policies and practices effectively secret from most of their users – for when users find out what is going on, they often object, and object strongly. Secondly, it suggests some of the possible ways to change things– firstly by raising awareness of practices so there are more objections; secondly by making it harder for companies to keep such practices secret; and thirdly by making it harder for companies to use practices which do not require real express, informed consent, of an ‘opt in’ rather than ‘opt out’ form.