Deepfake is an AI-based technology used to produce or alter video content so that it presents something that didn't, in fact, occur. The term is named for a Reddit user known as deepfakes who, in December 2017, used deep learning technology to edit the faces of celebrities onto people in pornographic video clips. The term, which applies to both the technologies and the videos created with it, is a portmanteau of deep learning and fake.
Deepfake video is created by using two competing AI systems -- one is called the generator and the other is called the discriminator. Basically, the generator creates a fake video clip and then asks the discriminator to determine whether the clip is real or fake. Each time the discriminator accurately identifies a video clip as being fake, it gives the generator a clue about what not to do when creating the next clip.
Together, the generator and discriminator form something called a generative adversarial network (GAN). The first step in establishing a GAN is to identify the desired output and create a training dataset for the generator. Once the generator begins creating an acceptable level of output, video clips can be fed to the discriminator.
As the generator gets better at creating fake video clips, the discriminator gets better at spotting them. Conversely, as the discriminator gets better at spotting fake video, the generator gets better at creating them.
Until recently, video content has been more difficult to alter in any substantial way. Because deepfakes are created through AI, however, they don't require the considerable skill that it would take to create a realistic video otherwise. Unfortunately, this means that just about anyone can create a deepfake to promote their chosen agenda. One danger is that people will take such videos at face value; another is that people will stop trusting in the validity of any video content at all.
Learn more about deepfakes and the technology behind them: