Facebook is probably the website you go to when you want to share personal information about yourself-- where you live, what you like, your music choices.
But you might be unintentionally sharing all that information and more when you're surfing the web or online shopping.
Many web sites use small digital files called cookies to collect details on everything from where you live to what clothes you buy. If you're security savvy, you've probably deleted cookies from your computer before.
"They [ad companies] can sell it to whomever they want. There's absolutely no law regulating the use of this data."Julia Angwin, Wall Street Journal reporter
But the Wall Street Journal recently reported that some web sites are now using so-called "supercookies" that are almost impossible for computer users to find and delete.
They've been deployed on websites like MSN.com and Hulu.com, but have since been removed.
All types of cookies, including supercookies, are used by ad companies to get more information about people surfing the web. Often that information is sold to companies who target their advertisements to your tastes.
Julia Angwin, reporter for the Wall Street Journal, told Here & Now's Sacha Pfeiffer that some people don't mind being tracked if it means they'll see advertisements tailored to their interests.
However, Angwin says, the lack of regulation on companies handling the vast amount of information available about us online may be cause for concern.
"They can sell it to whomever they want. There are employers who have looked into using this type of data, insurers have looked into using it. There's absolutely no law regulating the use of this data," she said.
- Wall Street Journal: What They Know
- Julia Angwin, senior technology editor for the Wall Street Journal
This segment aired on August 25, 2011.