Obama said if elected his government would "harness technology to confront the biggest challenges that America faces".

Rather than me sort of characterize the appropriateness or inappropriateness of what Donald Trump is doing at the moment, I think what we have to see is how will the President-elect operate, and how will his team operate, when they've been fully briefed on all these issues, they have their hands on all the levers of government, and they've got to start making decisions.

Global warming is not just the greatest environmental challenge facing our planet - it is one of our greatest challenges of any kind.

Even if the criticism is not always perfectly informed and in some cases I would deem unfair, just the noise, attention, fuss probably keeps powerful officials or agencies on their toes. And they should be on their toes when it comes to the use of deadly force.

The thing about hip-hop today is it's smart, it's insightful. The way they can communicate a complex message in a very short space is remarkable.

You haven't seen a lot of turnover in my campaign. And the culture of my campaign is one in which I think everybody feels a great sense of ownership.

The law is a powerful thing but the law doesn't always change what's in people's hearts. And so all of us have an obligation to think about how we're treating other people.