File Format Reference

HEIC is the default photo format used by every iPhone and iPad since iOS 11 (2017). It produces files roughly 50% smaller than JPEG at comparable quality, which is why Apple adopted it. The catch: almost nothing outside the Apple ecosystem can open it.

WebP is Google's open-source image format, designed to replace JPEG and PNG on the web. It produces files 25–35% smaller than equivalent JPEG or PNG images, supports transparency, and is supported by all modern browsers. The gap is everywhere else: image editors, messaging apps, and desktop software lag behind.

AVIF is the newest widely-deployed image format, based on the AV1 video codec. It achieves 40–50% smaller file sizes than PNG and outperforms WebP by around 20% — at the cost of slower encoding and incomplete software support. It's the future of web images, but not yet universal.

Opus is a modern open-source audio codec developed by Xiph.org and Mozilla. It powers voice and audio in Discord, Zoom, Google Meet, and every WebRTC application. It delivers remarkable audio quality at very low bitrates — outperforming MP3 at every bitrate — but almost no consumer software plays .opus files outside a browser.

WebM is Google's open, royalty-free video format designed for the web. It's smaller than MP4 for streaming, supported by all modern browsers, and the format screen recorders and web-based tools often use by default. Outside the browser, support is inconsistent.

EPUB is the open-standard ebook format used by Apple Books, Kobo, Google Play Books, and most non-Kindle ereaders. It wraps HTML, CSS, and images into a single file that reflows to fit any screen size. It is the ebook equivalent of HTML — adaptable, open, and widely supported, except on Kindle.