The websites we visit, the links we click, the personal details we reveal on Facebook-all of this can give companies insight into what internet ads we might be interested in seeing.
But privacy watchdogs warn that too many people have no idea that internet marketers are tracking their online habits and then mining that data to serve up targeted pitches-a practice known as behavioral advertising.
So the US congress could be stepping in. Rep Rick Boucher, chairman of a subcommittee on communications and the internet, is drafting a bill that would impose broad new rules on websites and advertisers. His goal: to ensure that consumers know what information is being collected about them on the web and how it is being used, and to give them control over that information.