A deepfake video presents a realistic AI-generated image of a real person saying or doing fictional things. Perhaps the most famous such video to date portrayed Barack Obama calling Donald Trump a "dipshit." Facebook is creating a "Deepfake Detection Challenge," which will offer grants and awards in excess of $10 million to people developing promising detection tools. The social network is teaming up with Microsoft and the Partnership on AI (which includes Amazon, Google, DeepMind, and IBM), as well as academics from MIT, Oxford, Cornell Tech, UC Berkeley, and others on the effort. The tech companies will contribute cash and technology and will help with judging detection tools, a Facebook spokesperson told me.