2006: Jack Dorsey sends the world’s first (non-automated) tweet:

inviting co-workers

The expression is as uninspiring as Alexander Graham Bell’s “Mr. Watson, come here, I want you,” which was uttered 130 years and a few days earlier. But it also heralds a new means of communication whose impact might rival even that of the telephone.

Five years on, Twitter is still derided by some as over-hyped, a vast wasteland of “I am eating a ham sandwich” irrelevancies and non sequiturs, almost as big a waste of time as Facebook.

But it has also been credited with accelerating revolutions, spawning new...

When Facebook first appeared, the issue of “to friend or not to friend” didn’t seem worth sweating over. After all, it wasn’t like this college-born networking service was central to your life or anything. Only now, for many of us, it pretty much is. And for too many of its half a billion active users, that carelessly assembled cohort known as the friend list has become a monster.

The list is the gateway through which people observe our major life events, casual musings, physical peregrinations, and crop yields on FarmVille. As Facebook engineers add more features, the...