How WebP stores images
WebP is a raster image format. A decoder reconstructs a grid of pixels from compressed data, much like it does for JPEG or PNG. Lossy WebP uses prediction and transform coding to reduce the amount of detail that must be stored; lossless WebP stores the pixel values exactly while still using compression.
The format also supports an alpha channel, so transparent edges in icons and illustrations can be retained. WebP can contain animation, but this GZ browser toolchain exports still images only; converting an animated source may discard motion.
When WebP is useful
WebP is a practical delivery format for websites when your audience uses current browsers. Photographs can often be stored smaller than a comparable JPEG, while transparent illustrations can be smaller than a PNG. The result varies with image content and encoding settings, so measure rather than assume.
Keep a source copy for editing. A lossy WebP is a delivery asset: repeatedly editing and re-encoding it can accumulate visible degradation. For line art, text-heavy graphics or exact pixels, compare PNG or lossless options before choosing.
Frequently asked questions
Is WebP always smaller?
No. File size depends on the source, quality, encoder and dimensions. Some images become larger after conversion.