AOMedia Video 1 (AV1) is an open, royalty-free video coding format initially designed for video transmissions over the Internet. It was developed as a successor to VP9 by the Alliance for Open Media (AOMedia),2 a consortium founded in 2015 that includes semiconductor firms, video on demand providers, video content producers, software development companies and web browser vendors. The AV1 bitstream specification includes a reference video codec.1 In 2018, Facebook conducted testing that approximated real-world conditions, and the AV1 reference encoder achieved 34%, 46.2%, and 50.3% higher data compression than libvpx-vp9, x264 High profile, and x264 Main profile respectively.3

Like VP9, but unlike Advanced Video Coding (AVC) and H.265 (HEVC), AV1 has a royalty-free licensing model that does not hinder adoption in open-source projects.456728

AVIF is an image file format that uses AV1 compression algorithms.

Source: Wikipedia