That old grocery-store standby, the bar code on every mop, magazine, and Mars bar, celebrated its 30th birthday this year. Considering the drastic advances in computing since 1974, it should come as no surprise that there's a new product-tracking technology breathing down the bar code's neck.

It's called the Electronic Product Code, and at its core, it's just a long number like the one embedded in a bar code. But whereas bar codes can only be read by laser scanners at close range, EPCs are stored in radio frequency ID (RFID) chips affixed to product packages, which radio-wave scanners can read at a distance of up to several meters. While all bags of Oreos bear the same bar code, Electronic Product Codes have so many digits that each bag could receive its own -- as could up to a billion billion other items.