The web is at a really important turning point right now. Up until recently, the default on the web has been that most things aren't social and most things don't use your real identity. We're building toward a web where the default is social.

Every application will be designed from the ground up to use real identity and friends.

The days of you having a different image for your work friends or co-workers and for the other people you know are probably coming to an end pretty quickly. Having two identities for yourself is an example of a lack of integrity.

After launching the first version of Facebook for a few thousand users, we would discuss how this should be built for the world. It wasn't even a thought that maybe it could be us. We always thought it would be someone else doing it.

You can use your real identity, or you can use phone numbers for something like WhatsApp, and pseudonyms for something like Instagram. But in any of those you're not just sharing and consuming content, you are also building relationships with people and building an understanding of people.

In a recent survey of Millennials around the world asking what most defines our identity, the most popular wasn't nationality, ethnicity or religion. It was "citizen of the world." That's a big deal. Every generation expands the circle of people we consider one of us. And in our generation, that now includes the whole world. This is the struggle of our time. The forces of freedom, openness, and global community against the forces of authoritarianism, isolationism, and nationalism - forces for the flow of knowledge, trade, and immigration, against those who would slow them down.