These young people have twice the presence in the population of that country as America's largest generation, Millennials (born 1982-2003), has in ours.

In the immediate aftermath of Iran's disputed presidential election, text messages became the tool for organizing post-election protests. Hundreds of thousands of tweets provided more, if not clearer, information about what was happening each day than traditional media. Opposition and government Facebook pages poured out dueling messages on the Internet.  It...