What information does EXIF metadata contain?
Most phone and camera photos carry hidden metadata beyond the pixels: the exact GPS coordinates where it was taken, the device model, the date and time down to the second, sometimes even the lens and exposure settings. None of that is visible when you look at the photo, which is exactly why it's easy to forget it's there before posting a photo publicly.
Why is EXIF removed by default instead of kept?
Because it's the safer default — for anyone sharing photos publicly, not carrying location and device data along unless there's a specific reason to is safer. If you do need to preserve it (for a personal photo archive, for example), the "keep EXIF" option is there, but it only works when the output format is JPEG — PNG and WebP don't support embedding this kind of metadata at all, so there's nothing to preserve if you're converting to those formats.
How do I fully protect photos before sharing them publicly?
Pair EXIF removal with a watermark. Stripping EXIF handles the metadata a photo carries; it doesn't do anything about someone reusing the image itself. For photos going onto a public listing, portfolio, or marketplace, combining this with a watermark (see the watermark tool) covers both angles — hidden data removed, visible ownership signal added — in the same batch.