PNG
Portable Network Graphics (PNG) is a free lossless image file format released in 1996. It was ceated as an alternative to GIF, which was at the time a proprietary format. It gained animation support similar to GIF with the release of APNG in 2008, which is now supported by all popular web browsers.
Performance Checklist
Lossless? Yes
Lossy? No
Supported Bit Depths: 8 BPC, 16 BPC
HDR/Wide Gamut? Yes
Animation? Yes
Transparency? Yes
Progressive Decode? Kinda
Royalty Free? Yes