Bruce Schneier, a fellow at the Berkman Klein Center for Internet & Society at Harvard University, said the Yahoo breach was very serious because so many Internet users routinely store sensitive data on Internet-based systems — not on the hard drives in their desktop PCs, for example. “We no longer keep our stuff on our computers,” he said. “We keep our stuff on their computers.”

Source: Yahoo hack is one of the largest security breaches of the Internet age – The Boston Globe