Wal-Mart this week will begin promoting a new privacy policy on its Web site, on signs in its stores, and in e-mails to about 15 million customers.

For the first time, the privacy policy of the world's largest retailer will cover both physical stores and online operations, and it gives customers more control over what data they share with the company. The new policy goes into effect in August.

Wal-Mart wouldn't discuss plans for how it might use personal data, but the policy suggests it's looking to more aggressively market through new channels, including text messages to mobile phones, and to share more data with its partners.

The 3,500-word policy focuses on when and how Wal-Mart collects data from customers and on how data gets used. Customers may select their preferrred communication channels at a new privacy preference center on Walmart.com. The company said it won't send marketing messages or surveys or share information with third parties for marketing purposes unless customers opt-in at the preference center.

"We want to provide customers with more control over their own data, which is a big topic today for relationships with customers and their privacy," said Zoe Strickland, in an interview. Strickland became Wal-Mart's first chief privacy officer three years ago, following a similar job at the U.S. Postal Service.

The updated policy has "stricter standards," among them the opt-in requirement for certain communications, Strickland explained. The previous policy made no references to channels such as text messages and third-party telemarketing.

For the first time, Wal-Mart said it may share information with "selected vendors who may offer you products and services of interest," the policy reads. For that to happen, however, customers must opt-in.

Strickland said her team worked closely with Wal-Mart's marketing and business intelligence groups in developing the new policy.

The policy reflects Wal-Mart's range of businesses -- with details about data collected at pharmacies, banking, and vision centers. For example, it notes that by law, Wal-Mart collects data on purchases of pseudoephedrine, sometimes used illegally to make methamphetamine.

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