There are more than 200 million adults and more than 18 million businesses in the United States, and there's data available on each one. You can buy data on just about every kind of industry, product, habit, trend, and interest. All that information can be sliced and diced, filtered and analyzed, massaged and repackaged in just about any manner that suits your needs.

Information is power--and the decisions about the best way to use and sell data are becoming more complex. Companies aren't sure whether to look at their data as a source of revenue or a closely guarded competitive advantage. Last month, drug retailers that handle a third of the nation's prescriptions--including CVS, Kmart, and Wal-Mart--banded together to pool up-to-the-minute sales data from thousands of stores nationwide and sell that information to marketing companies and drugmakers, which spend up to $25 million annually for such data to track sales trends and market share.

Several months earlier, however, Wal-Mart decided to stop selling general sales data to six market-research companies that combined the data with information from other companies to create industrywide reports on retail sales trends. "Our competitors were getting more out of the third-party aggregation than we were, so it made more sense for us to stop," a Wal-Mart spokesman says.

While the lack of sales data from one of the largest retailers in the world will hurt, competitors can turn to hundreds of information brokers to fill the gaps. Thanks to the Internet, collecting and analyzing customer data is easier and more widespread than ever before. Though the practice of collecting data about consumers is decades old, the Internet and its ability to collect data so easily have spurred new protests from privacy groups.

Jennifer Barrett, chief privacy officer at Acxiom Corp., one of the biggest collectors of customer data, says it's easy to understand why many of the protests center on the Internet. "Consumer concerns are greater online because the collection is a little less obvious," she says. Barrett adds that Acxiom doesn't collect information online because "the data we're interested in isn't available online."

Most of the consumer information available for sale is compiled from public sources that are easy to locate, and most of the data is used to create mailing lists that fuel the direct marketing of products and services. The key to successful list creation lies in being able to augment and correlate basic name and address information with enough other data about individual consumers' interests and buying habits to be able to generate narrowly focused marketing lists.

"Few consumers could write down even 1% of the amount of data that companies have about them," says Jason Catlett, president of Junkbusters Corp., a nonprofit privacy advocacy group in Green Brook, N.J. Catlett estimates that a typical person's name and address are known to 500 companies or more. "These companies know what you buy, how much you spend, and how frequently you buy."

That information is worth a lot of money. The Direct Marketing Association--the trade group that represents the companies that market their products using offers delivered via mail, telephone, magazines, the Internet, radio, or TV--says companies spent $191 billion last year on direct-response advertising, the category that includes direct mail and telephone solicitations, and those efforts produced $1.7 trillion in revenue.

Government records can yield information on a person's history of bankruptcies, tax liens, and civil judgments, as well as criminal background information. Other information available from public records includes civil litigation histories, outstanding state or federal warrants, and professional licenses issued for fields that require them, such as medicine. Records of property ownership are also available, as are marriage and birth records, divorce records, business licenses, and land-ownership records.

For businesses such as Acxiom, DoubleClick, Equifax, Experian, and TransUnion, public records are merely the starting point for sophisticated information products that mix and match consumer data from hundreds of sources nationwide. TransUnion, for example, claims to have detailed data on 200 million people, or every active consumer in the United States.

Once the companies get consumers' names, addresses, and phone numbers, they combine basic demographic data with more personalized data they get from other sources, including product warranty cards and consumer surveys, to generate lists that target specific segments of the population. Big list brokers sell mailing lists, usually for one-time use by customers such as catalog companies. The average cost is about $150 for every 1,000 names on the list, says Patricia Faley, VP of ethics and consumer affairs at the Direct Marketing Association.

Even though lists are for single use only, once a business turns a prospect from the list into a customer, the business can add the new consumer to its own list. Records on consumers also are exchanged when companies, including the large list houses, trade lists of equivalent size or value, a fairly common practice that lets them refresh their lists without the expense of buying a new one or collecting brand-new data.

Lands' End Inc., which sells clothing online and via catalogs, doesn't sell lists of customers, but it does trade names with a handful of companies whose merchandise matches the interests of Lands' End shoppers, a spokeswoman says. "We don't do it for profit; we only do it if we perceive a value for our customers," she says. The Dodgeville, Wis., company does buy catalog lists from other companies, which it adds to its house list.

Another well-known source of data is credit reports, which typically cost $15 to $20 when bought by a business. The top three credit bureaus that maintain credit reports about individual consumers are Equifax, Experian, and TransUnion, which are also major players in the list business.

Credit reports contain identifying information such as name, address, marital status, Social Security number, birth date, and employment information. They also include an individual's credit information, including credit account numbers and information on the timeliness of an individual's payments. Another section contains public information such as records of tax liens and court judgments. Finally, they include records of how often the report has been reviewed and by whom.

Selling products and services isn't the only reason to seek out data on an individual. Companies often conduct background checks on potential employees, using investigators or firms that specialize in such services. Confichek.com, a Sacramento, Calif., private-investigation firm, offers to conduct a criminal background search via the Internet for $15 per county; a search for bankruptcies, tax liens, and judgments for $5; a search of civil records for $20 per county, plus costs; or a search of wants and warrants for $20 for each state searched.

Business or commercial credit reports, available from a variety of sources, are more complex and can cost far more. The charge for a very basic commercial credit report can start as low as $50, but the price rises relative to the amount of data covered and the size of the company reported on.

Dun & Bradstreet, a provider of business credit information, maintains credit records on 65 million businesses in some 200 countries. Of those records, 23 million are in the United States, and at least 13 million are for active businesses. The remainder have either gone out of business or are from companies that have been registered but that never actually began operations, says Sandy Stoker, VP of data business development at Dun & Bradstreet. The 160-year-old company gets data for its reports from public records and from 5,300 businesses that provide information such as accounts-payable records, Stoker says. To keep its records current, the company continually verifies its data, refreshing its databases 1 million times a day.

The company offers four types of data products. The first consists of "firmographics" such as the names, addresses, and sizes of businesses. The second consists of value-added data about businesses, in which Dun & Bradstreet can qualify or categorize companies according to 1,600 data types. A third type of product tracks relationships among businesses, including ownership links. The fourth, known as predictive products, are the most powerful and cost the most. The latter category, Stoker says, "scores" subject companies in areas such as the likelihood that they will pay bills on time or the chances that they will go out of business.

The bottom line: The right information will pay for itself. "A good mailing list can produce a couple of millions of dollars in sales all by itself," says Jim Workman, CEO of BFW Advertising Inc., a Boca Raton, Fla., ad agency that builds and refines list databases for clients. A highly targeted list that produces sales "is a corporate asset that's worth its weight in gold." --with Christopher T. Heun