Synthetic audio, video or images of a real person doing or saying something they did not. Quality has improved to the point where a convincing voice clone can be made from a short sample, and the most common harms are not political: they are fraud, where somebody impersonates a senior colleague to authorise a payment, and non-consensual sexual imagery, which overwhelmingly targets women.
Technical view
Produced by diffusion models and voice cloning systems that need very little reference material. Detection is an arms race detectors are losing, since each generation of detector becomes training signal for the next generation of generator, and detector performance degrades badly under compression and re-encoding. The more durable defences are procedural rather than technical: verification through a separate channel for anything consequential, agreed code words for payment authorisation, and provenance standards applied at the point of capture.
Related
Part of AI Terminology Index, section: Society and Impact.