The AV1 codec was developed Alliance for Open Media (AOMedia), 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. In 2018, Facebook, testing real world conditions, AV1 achieved 34%, 46.2% and 50.3% higher data compression than libvpx-vp9, x264 high profile, and x264 main profile respectively.
Feature wise, AV1 is specifically designed for real-time applications (especially WebRTC) and higher resolutions (wider color gamuts, higher frame rates, UHD) than typical usage scenarios of the current generation (H.264) of video formats where it is expected to achieve its biggest efficiency gains. It is therefore planned to support the color space from ITU-R Recommendation BT.2020 and up to 12 bits of precision per color component. AV1 is primarily intended for lossy encoding, although lossless compression is supported as well.
Historically the AVI format supported lossless as well as compressed video formats. The main problem with AVI was the lack of meta tags for media description. AVI was codec agnostic and it depends on hardware vendors for support.
The most obvious advantage of AV1 is that it is royalty free. This could lead to lower costs for Blu-Ray and streaming services would also be lower cost. The patent on MP3, MPEG-2 and GIF are now expiring or already have expired. Adoption of AV1 with open source tools will be almost immediate. Commercial products will be able to update their products as well.
Apple is sticking with their H.264 MPEG license for media. AV1 can reduce the file sizes of video substantially so its likely Apple will adopt the codec. Apple has been slow to modernize even with $1 billion in cash on hand.