WebP (WebP Wikipedia entry) & WebM (WebM Wikipedia Entry) are open source image & video formats respectively that allow greater image compression than traditional formats like JPEG and PNG. They're backed by Google, and most modern browsers support them (caniuse on WebP support). Support outside of browsers is still growing. When I last tried a few months ago, WordPress didn't seem to natively recognize .webp files. They now work fine. Despite growing support, many Adobe programs still don't recognize or export to these formats, requiring you to use external converters.
These formats are important for small media-heavy sites like cass-e.net because they can help reduce server bandwidth and load times. So it's a little frustrating when processing these files requires extra steps.
I came across this plugin by fnord adding WebM exports to Adobe Media Encoder while getting my recent physical project ready for posting. I planned to include a few short videos demoing functionality, and I wanted to use either animated .webp or .webm files. The project was running a few days later than I'd hoped, so I was on the lookout for time-saving measures and I ran into their plugin, allowing me to export directly to that format from Premiere. It worked well! I also appreciate that their plugins are open source.
fnord also has a (beta) Photoshop plugin adding WebP support on GitHub here although it hasn't been updated since 2017, and I haven't tested it.
While doing research for this post I came across WebPShop, a Photoshop plugin adding WebP Support on the WebM project GitHub.
My recent post with short demo videos that take advantage of this plugin's direct export capability: