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What's a billion gigabytes? An exabyte

Megabytes are dead.

Gigabytes are passe.

So much digital data now moves around the globe that those who endeavor to measure it employ a new — or new to non-nerds — term:

The exabyte.

How much data is an exabyte? It's a billion gigabytes — and it signifies just how digital and data-intensive the world has become.

In 2007, the global capacity to store digital information — on computer hard disks, smartphones, CDs and other digital media — totaled 276 exabytes, a new report finds.

How much is that? Imagine a stack of CDs — each holding an album's worth of digital music — shooting from the top of your desk to 50,000 miles beyond the moon.

But not everyone has equal access to those resources. In fact, the digital gap between rich and poor countries appears to be growing, said Martin Hilbert, of the University of Southern California, who led the audacious effort to tally all of civilization's information and computing power.

In 2002, people in developed countries had access to eight times the bandwidth — or information-carrying capacity — of people in poorer nations, Hilbert said, citing data he will publish soon. By 2007, that gap had almost doubled.

"If we want to understand the vast social changes under way in the world, we have to understand how much information people are handling," Hilbert said.

To address that question, Hilbert and co-author Priscila Lopez spent four years poring over 1,110 sources of information spanning from 1986 to 2007, including sales data from computer and cell phone makers and the music and movie industries.

In 2002, digital storage capacity outstripped the non-digital variety — mostly paper and videotapes — for the first time.

"That was the turning point," said Hilbert, who published the report in the journal Science. "You could say the digital age started in 2002. It continued tremendously from there."

By 2007, the last year documented in the study, 94 percent of all information storage capacity on Earth was digital.

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