Three formats support transparency, each best for a different job.
PNG
The universal choice for transparent photo cutouts and detailed graphics. Works everywhere, but files can be large.
WebP
Same transparency as PNG, usually 25–35% smaller. Great for the web when you don't need legacy-browser support.
SVG
A vector format — perfect for logos and icons because it stays razor-sharp at any size and has tiny file sizes. Not for photos.
How to make one
Need to cut out a subject? Use remove background. Have a transparent PNG you want smaller? Convert it to WebP. For why JPG can't do this, see transparency turning black.