HEIF and ICO explained
HEIF is the underlying container standard that HEIC is a specific profile of. The distinction matters mainly to developers: HEIF describes the box structure, while HEIC specifies HEVC-compressed contents inside it.
ICO is a container that holds several versions of the same icon at different sizes, so the operating system or browser can pick the one that fits. It is capped at 256×256 pixels.
- Where HEIF files come from
- Newer cameras and some Android devices, alongside Apple's HEIC.
- Where ICO is used
- Website favicons and Windows application icons.