Facebook succeeded because it was about real people having a presence on the Internet. There were all these other social networking sites people had, but they were all about fictional people.

An entrepreneur must deal with more uncertainty than a professional with a well-defined role.

I don't think success is complicated; if you do something that works, then it's a success.

It's good to test yourself and develop your talents and ambitions as fully as you can and achieve greater success; but I think success is the feeling you get from a job well done, and the key thing is to do the work.

'Perfect competition' is considered both the ideal and the default state in Economics 101. So-called perfectly competitive markets achieve equilibrium when producer supply meets consumer demand.

The next Bill Gates will not start an operating system. The next Larry Page won't start a search engine. The next Mark Zuckerberg won't start a social network company. If you are copying these people, you are not learning from them.

Technology just means information technology.

People don't want to believe that technology is broken. Pharmaceuticals, robotics, artificial intelligence, nanotechnology - all these areas where the progress has been a lot more limited than people think. And the question is why.

Monopolies are bad and deserve their reputation when things are static and the monopolies function as toll collectors... But I think they're quite positive when they're dynamic and do something new.

From my perspective, I think the question of how we build a better future is an extremely important overarching question, and I think it's become obscured from us because we no longer think it's possible to have a meaningful conversation about the future.

We live in a world in which courage is in less supply than genius.

Contrarian thinking doesn't make any sense unless the world still has secrets left to give up.

When people use the word 'science,' it's often a tell, like in poker, that you're bluffing.

Airbnb is undervalued.

The future is limitless.

Properly defined, a startup is the largest group of people you can convince of a plan to build a different future.

A diploma is a dunce hat in disguise.

People always say you should live your life as if it were your last day. I think you should live your life as though it will go on for ever; that every day is so good that you don't want it to end.

Every one of today's smartphones has thousands of times more processing power than the computers that guided astronauts to the moon.

You can achieve difficult things, but you can't achieve the impossible.

Spiraling demand for resources of which our world contains a finite supply is the great long-term threat posed by globalisation. That is why we need new technology to relieve it.

Great things happen only once.

If I had known how hard it would be to do something new, particularly in the payments industry, I would never have started PayPal. That's why nobody with long experience in banking had done it. You needed to be naive enough to think that new things could be done.

The most successful businesses have an idea for the future that's very different from the present - and that's not fully valued.

Creating value isn't enough - you also need to capture some of the value you create.

When I was a kid, the great debate was about how to defeat the Soviet Union. And we won. Now we are told that the great debate is about who gets to use which bathroom. This is a distraction from our real problems. Who cares?

It is true that you can say that death is natural, but it is also natural to fight death. But if you stand up and say this is a big problem, we should do something about this, that makes people very uncomfortable, because they've made their peace with death.

Men and machines are good at different things. People form plans and make decisions in complicated situations. We are less good at making sense of enormous amounts of data. Computers are exactly the opposite: they excel at efficient data processing but struggle to make basic judgments that would be simple for any human.

The core problem in our society is political correctness.

The best start-ups might be considered slightly less extreme kinds of cults. The biggest difference is that cults tend to be fanatically wrong about something important. People at a successful start-up are fanatically right about something those outside it have missed.

People are spending way too much time thinking about climate change, way too little thinking about AI.

Investors are always biased to invest in things they themselves understand. So venture capitalists like Uber because they like driving in black town cars. They don't like Airbnb because they like staying in five-star hotels, not sleeping on people's couches.

Every time you write an email, it is in the public domain. There are all these ways where security is not as good as people believe.

Ideally, I want us to be working on things where if we're not working on them, they won't happen; companies where if we don't fund them they will not receive funding.

When I moved to Cleveland, defense research was laying the foundations for the Internet. The Apollo program was just about to put a man on the moon - and it was Neil Armstrong, from right here in Ohio. The future felt limitless. But today, our government is broken.

I did not want to write just another business book.

I think competition can make people stronger at whatever it is they're competing on. If we're competing in some athletic event for competitive swimmers, really intensely competing, it's likely that both of us will become better, but it's also quite possible we'll lose sight of what's truly valuable.

I suspect Obama did not know he was recording Angela Merkel's cell phones.

I do think there is this danger that our society has made its peace with decline. I'd like to jolt them out of their complacency a little bit.

I think people in Europe are generally pessimistic about the future. They have low expectations; they're not working hard to change things. When you're a slacker with a pessimistic view of the future, you're likely to meet those expectations.

I worked at a law firm in New York very briefly.

I'm very pro-science and pro-technology; I believe that these have been key drivers of progress in the world in the last centuries.

How to teach people to do what hasn't been done is a great riddle.

I think anything that requires real global breakthroughs requires a degree of intensity and sustained effort that cannot be done part time, so it's something you have to do around the clock, and that doesn't compute with our existing educational system.

Americans mythologize competition and credit it with saving us from socialist bread lines. Actually, capitalism and competition are opposites. Capitalism is premised on the accumulation of capital, but under perfect competition, all profits get competed away.

There's absolutely no bubble in technology.

People are worried about privacy, and its one of the reasons people are using a service like SnapChat.

Whenever I talk to people who founded a company, I often like to ask the prehistory questions 'When did you meet? How long have you been working before you started the company?' A bad answer is, 'We met at a networking event a week ago, and we started a company because we both want to be entrepreneurs.'

Don't bother starting the 10,000th restaurant in Manhattan. Find something to do that if you don't do it, it won't get done.

One of my first investments was $100,000 in a Web-based calendar startup - and I lost every dollar.