Where it came from
WebP was released by Google in September 2010, built on the intra-frame compression of the VP8 video codec Google acquired with On2 Technologies. Lossless mode (VP8L) and alpha transparency arrived in 2011, animation in 2012. Adoption stalled for most of a decade because Safari refused to ship it, so sites had to serve fallbacks anyway. That ended in September 2020 when Apple enabled WebP in Safari 14, macOS Big Sur and iOS 14 — overnight the format became genuinely universal in browsers. Today Next.js, Cloudflare, Cloudinary, imgix, WordPress and Shopify all emit WebP by default, which is why so many images saved from the web now land on disk as a .webp file.
Two modes in one format
WebP has a lossy mode built on VP8's intra-frame compression and a lossless mode called VP8L. Lossy is for photographs and typically lands 25-35% below an equivalent-quality JPEG. Lossless is for logos, icons, screenshots and line art, and beats PNG by roughly 26% on the same pixels. Both modes support full 8-bit alpha, which is unusual — JPEG has no transparency at all.
Animation
WebP supports animation, and it comprehensively outclasses GIF at it: 16 million colours instead of 256, and files routinely 60-80% smaller. Anywhere you can serve animated WebP rather than GIF, you should.
What it is bad at
WebP is 8-bit and sRGB only — no HDR, no wide gamut, no 10- or 12-bit depth, which is where AVIF pulls ahead. Neither edge can exceed 16383 pixels. And it is a delivery format, not a working format: it has no layers, no ICC-managed CMYK and no place in a print pipeline.
The compatibility gap
Browsers render WebP universally. Desktop software does not. Photoshop only added support in 23.2, Office in 2021, and Outlook still will not render one inline. This gap between 'displays fine in my browser' and 'my software refuses it' is the single most common frustration with the format, and the reason converters like this one exist.