"The idea, though, of lifestreams has been catching on. A lifestream is a way of organizing digital objects—photos, emails, documents, Web links, music—in a time-ordered series. A timeline, in essence, that extends into the past but also the future (with appointments, to-do lists, etc.). Facebook, with its 'wall' constantly updated with postings by you and your friends, is a lifestream. Twitter's feed is a lifestream. 'Chatter,' developed by Salesforce.com for internal use by client companies, is a lifestream.

Mr. Gelernter believes streams are a more intuitive, useful way to organize our digital lives, not least because, as the past and future run off either side of our screen, at the center is now—and now is what the Internet really is about."