JPEG and PNG have been the standard web image formats since roughly the dawn of the web itself. Newer formats — WebP, and more recently AVIF — do the same basic job, at meaningfully smaller file sizes, and most modern browsers now support them without any extra work from a visitor.
What actually changed
JPEG and PNG were both designed decades ago, under very different constraints than today's web. Newer formats use more efficient compression techniques developed since then, so they can produce a visually similar image at a fraction of the file size — often 25-50% smaller than an equivalent JPEG, and sometimes more.
WebP vs. AVIF, briefly
- WebP, developed by Google, is now supported by essentially every current browser. It's a safe, well-established default for most sites.
- AVIF is newer and can compress even further in many cases, with support that's now strong across major browsers as well, though it can be slightly slower to encode.
For most small business sites, switching from JPEG/PNG to WebP is the highest-value, lowest-risk move. AVIF is worth adding as a further optimization once WebP is in place.
Why this matters beyond "smaller files"
Images are typically the single largest contributor to page weight (see our guide to website speed). Smaller image files mean faster load times, which means fewer visitors bouncing before the page finishes loading, and a small but real boost to search rankings, since page speed is a factor there too.
<picture> element to offer AVIF or WebP to browsers that support it, with a JPEG or PNG fallback for anything older — visitors get the best format their browser can handle automatically.What to actually do about it
If your site is on WordPress or a similar platform, a number of plugins will automatically convert and serve modern formats without touching your existing image library. On a custom-built site, this is typically handled as part of an image pipeline during a build or a performance pass.
The bottom line
Modern image formats are one of the rare web upgrades that are almost entirely upside: smaller files, faster pages, no visible quality loss for most photography, and no cost to visitors. If your site is still serving plain JPEGs and PNGs everywhere, it's a straightforward, high-value update.