A wealth of information exists in commercial databases detailing who you are, what you buy and where you go. While amassing information about people in order to better market to them isn’t new, today it’s a multibillion-dollar industry because of the sheer volume of data available.

“No one even knows how many companies there are trafficking in our data,” reports 60 Minutes correspondent Steve Kroft. “But it’s certainly in the thousands and would include research firms, all sorts of Internet companies, advertisers, retailers and trade associations. The largest data broker is Acxiom, a marketing giant that brags it has on average 1,500 pieces of information on more than 200 million Americans.”

The information these companies are gathering includes not just your name and contact details, but things you might not want anyone to know such as your sexual orientation, religion and medical conditions — all of which could even be made available to a prospective employer trying to decide whether to hire you.

So who’s collecting information on you, and what are they collecting? Read on to find out.

Credit card companies

Buy a lot of booze or spend a lot of money on cosmetics? Your purchases — at least if you’re using a debit or credit card to make them — are no secret. For example, MasterCard and the digital ad firm Maxpoint spent about six months putting into place a system through which Maxpoint could use purchase histories to target ads to certain demographics.

“The MasterCard data shows how high or low people index within a specific ZIP code for certain types of purchases,” reports AdAge. “Using the MasterCard data, a burger or pizza chain might use the system to push promotions to neighborhoods in which people spend more than the average at fast-food joints.”

What you can do: Pay cash for things you don’t want anyone knowing you buy.

Cellular carriers

Your cellular provider knows a lot about you. I checked Verizon’s privacy policy, for example, which says the company collects information including “call records, websites visited, wireless location, application and feature usage, network traffic data, product- and device-specific information, service options you choose, mobile and device numbers, video streaming and video packages and usage, movie rental and purchase data, FiOS TV viewership, and other similar information.”

To better hone its marketing offers, Verizon combines all that data with information it gets from outside companies that collect consumer demographics and interests. So if if you’re a Verizon customer, the company may know your gender and age and whether you like sports or own a pet.

“We may combine this information in a manner that does not personally identify you and use it to prepare aggregated business and marketing reports that we may use ourselves or share with others for their use,” the policy reads. “We may also share location information with other companies in a way that does not personally identify you so that they may produce business and marketing reports. You have a choice about whether your information is included in these reports.”

What you can do: Power down your phone if you don’t want your location known. Also check your carrier’s privacy policy; you can often opt out from having your personal information shared with third parties.

Cable and satellite companies

If you buy TV programming, the shows you watch can be tracked as well. The privacy policy of my satellite TV provider, DirecTV, states: “We may collect certain information about your use of a DIRECTV Receiver, Authorized Device or Authorized Application, about your viewing choices (such as programming packages you subscribe to, Pay Per View orders you place, and specific programs you access), and about your use of DIRECTV programming and services.”

As for how the company will share information, DirecTV says, in part: “We may also share your information with third parties: (1) that own content and technologies used in our products and services to report on and account for use of such content and technologies by our subscribers; or (2) with whom we offer co-branded, joint or customized products or services. We take reasonable steps to require these third parties to safeguard your personally identifiable information.”

What you can do: Check your provider’s privacy policy. If what the company is doing bothers you, there’s always the option of cutting the cord and sticking with free TV.

Retailers

Sometimes retailers may ask for your ZIP code in order to determine where to build new stores, but they can also use it to find out more about you from commercial databases, such as your mailing or email address, demographic information and buying habits. All this information helps them better market to you, but it also could end up being sold to data brokers.

The exception to this is what happens at the gas pump.

“Asking for the ZIP code at the pump is security-related,” Jeff Lenard, industry advocacy vice president for the National Association of Convenience Stores, told Forbes. “Someone with a stolen card would be less likely to correctly enter the ZIP. Thieves often test cards to see if they are still ‘live’ at places where they don’t have to engage in a face-to-face transaction, such as at the gas pump. This is done so that there is not a confrontation where they could have the card confiscated.”

What you can do: Refuse to provide a ZIP code or offer a fake one unless you’re at a gas pump.

Your vehicle

Modern telematics and embedded cellular features in newer vehicles allow many car manufacturers to remotely assess things such as engine and transmission performance and airbag deployment to aid in assessing crashworthiness, vehicle reliability and product development. How a manufacturer uses information about your car will vary.

If you subscribe to a service such as OnStar, you might wonder how it uses information about your vehicle’s speed and location. According to the company’s privacy policy, OnStar does not continuously monitor the speed and location of a vehicle or whether or not cabin inhabitants are wearing seat belts; it does so only when a customer is engaged with the company to do things like get help or navigation.

“OnStar does not sell identifiable customer location data to third parties,” an OnStar spokesperson informed me via email.

What you can do: Check your vehicle manufacturer’s privacy policy to see what kinds of information it is gathering as well as if and how you can opt out.

Data brokers

Once your personal information has been collected, it can fall into the hands of data brokers. To see some of the many sites collecting information about yourself, try searching for your name at Pipl.com. I did, and I found all sorts of sites gathering my data. Pipl offered maps to my house as well as a link to my wish list on Amazon, which also lists my birthday.

The Privacy Rights Clearinghouse provides an excellent listing of the scads of online information brokers that may be collecting information about you, plus links to help you opt out at those sites, if they are available. Unlistmy.info also provides a list of the most popular sites that might be storing data about you, as well as advice for getting off those lists (if that option exists).

The bottom line

The bottom line is that your personal information is most assuredly being collected and stored. Let that sink in: Just take a minute to think about who knows what you’re doing at any given moment and whether you care if your actions are being recorded.

Do you trust the company you’re doing business with to keep your data private? If not, only you can decide if the convenience of using your phone or making a purchase is worth the risk of making that information public.

This article was written by Christina DesMarais and originally appeared on Techlicious.

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