AVIFs Transparency data is stored using alpha channels. Both objects and images can have transparency data. Images can be rendered with defined opacities to display objects.
To add more context, transparency in image formats refers to the ability to specify how transparent or opaque each pixel in the image should be. This is often used to create the illusion of see-through areas in an image, such as when creating a logo with a transparent background. Alpha channels are used to store this transparency data, and in AVIF, they can be used to create both transparent objects and images. By rendering images with defined opacities, it is possible to display these transparent objects on top of other images or backgrounds. This can be useful for creating composites or layering images in a way that looks natural and seamless.