Think of it as a bar code for your bra.

Tiny wireless identification tags are soon going to start showing up throughout your daily life. If you have an E-ZPass transponder in your car or one of several Swatch watches on your wrist, you're already carrying a wireless tag. Your house, your food and even your clothes might someday be permeated with such tags, which can be read without your permission or knowledge.

Think I'm crazy? Last November, Texas Instruments and the Gap announced that they had completed a three-month test in which every piece of denim in a store in Atlanta received a wireless ID tag. This technology, boasts TI, allows each item of clothing to be tracked from the warehouse to the shelf to the checkout counter. Some of the largest retailers and consumer products firms, including Coca-Cola, Home Depot, Procter and Gamble and Wal-Mart, have joined to create standards to make sure that future tags and readers will all be compatible. That work is being done at the MIT-based Auto-ID Center.

By themselves, these tags seem harmless enough. Hit one with a radio beam at the right frequency, and it spurts out its unique serial number; that's why they're known as radio frequency identification (RFID) tags. E-ZPass uses the serial number to debit a driver's account when he or she passes through a tollbooth; companies like the Gap and Coca-Cola will use it to track inventory. Many animal shelters now have devices to look for tags implanted in lost household pets, speeding their return to their owners. Ranchers track cattle by implanting tags in the animals' ears. Futurists say that one day we might have houses filled with RFID readers and use them to find lost glasses, key chains and other tagged items.

The first mass application for these radio-read tags, however, will be inventory management and control. Playtex might put a tag in each bra to make sure that shipments destined for Asia aren't diverted to New York, where consumers are likely to pay more. Pass a reader over a box of bras and every undergarment will sing back its serial number. This allows for more accurate inventory control than tracking boxes does; individually serialized garments also make it dramatically harder for corrupt employees at a warehouse or trucking company to make a few bras "disappear," since automated readers will continually log the whereabouts of every item.