I appreciate your comments with regard to the data use policy and the statement of rights and responsibilities. We take very seriously the obligation to be transparent with our users. We try to present information about our data use practices in a number of different ways that are easy for people to understand. So I'm glad to hear you've found that the data use policy falls into that category.
The provision of the data use policy that you mentioned talks about the information we receive. Largely this is consistent with the way most websites on the Internet operate. Whenever you click on something on Facebook, whenever you interact with something, your Web browser sends a message to Facebook that says, send me back this information. So we keep records of those interactions. Those are retained on an ongoing basis. We have, for different kinds of information, different retention periods, so in some cases information will roll off, and by “roll off” I mean either be deleted entirely or be rendered anonymous by removing personal identifiers on a rolling basis, typically every 90 days for social plug-in impressions, for example. With regard to other data, there are different retention periods.
You mentioned search information specifically. When people search on Facebook, we collect that information, as I've said. We store it in an activity log, which is one of the tools I've talked about. That allows you to go back and look at all the things you've searched for. You can delete those any time just by clicking the delete button that appears next to each search. The goal there is, again, to be transparent with people about the information we have. That information is used right now to improve the service so we can make our search functionality better by knowing what people are searching for and what they're clicking on. Those are the main purposes for which we use that information. There are also our technical, debugging kinds of uses as well.
You also raised a second question with regard to our business model and how Facebook makes money. I think it's an important point that we try to stress to our users and to make sure people understand. The main Facebook business model is we operate Facebook and offer it for free to users who want to use it. In exchange, we pay for it by showing advertising on Facebook. We have a page called “Ads on Facebook” that provides information about how this works. In general, when you post information on Facebook, for example, information about your interests, you like a page that is relating to a particular topic, that's information we might use to decide which ads to show you.
Advertisers will come to us and will say I'd like to show this ad to people who are interested in a particular topic. We'll show the advertising to the users. Obviously we don't provide individual information back to the advertiser about who's seeing the ad, but we'll provide general information that a certain number of people have seen the ad. That way we hope we give people control over the information they've given to us, but that we also are able to use that information to show them advertising that's more relevant to them than what they otherwise would receive.