The 10-digit phone number system has more than 10 billion possible numbers for the country. And, of course, now, long-distance calling is just part of the telephone system.

The 10-digit phone number system has more than 10 billion possible numbers for the country. And, of course, now, long-distance calling is just part of the telephone system.

Just as our physical immune system helps our bodies defend against harmful invaders, digital immune systems protect organizations from threats and disruptions.

A movement is underway to create a digital identity system that would allow people to carry their ID on their phones or on digital smart cards and, eventually, use them over the internet. That might ...