WebP is a modern image format that provides superior lossless and lossy compression for images on the web. Using WebP, webmasters and web developers can create smaller, richer images that make the web faster.
Technical Specifications
VP8 key frame encoding (lossy) or LZ77 entropy coding (lossless). Supports animation and transparency.
Advantages
Smaller file sizes than PNG and JPEG, supports both transparency and animation.
Disadvantages
Not supported by very old browsers (though support is now very high).