There are a few other things that I built when I was at Harvard that were kind of smaller versions of Facebook.

We help Chinese companies grow their customers abroad. They use Facebook ads to find more customers. For example, Lenovo used Facebook ads to sell its new phone. In China, I also see economic growth. We admire it.

For the first time we're allowing developers who don't work at Facebook to develop applications just as if they were. That's a big deal because it means that all developers have a new way of doing business if they choose to take advantage of it. There are whole companies that are forming whose only product is a Facebook Platform application.

Google, I think, in some ways, is more competitive and certainly is trying to build their own little version of Facebook.

We think the fact that Instagram is connected to other services beyond Facebook is an important part of the experience...This is an important milestone for Facebook because it's the first time we've ever acquired a product and company with so many users.

Facebook is uniquely positioned to answer questions that people have, like, what sushi restaurants have my friends gone to in New York lately and liked? These are queries you could potentially do with Facebook that you couldn't do with anything else, we just have to do it.