What is WebP?

Google's format for the web, and a genuine improvement on both of the formats it replaces: lossy like JPG or lossless like PNG, transparency either way, and usually about 30% smaller. Every current browser reads it. Software that stopped being updated around 2019 often doesn't.

What is BMP?

The Windows bitmap, which stores pixels raw with no compression worth mentioning. Files are enormous. It survives because it's trivial to read - if you're writing an image loader from scratch or feeding an embedded display, BMP is the format that needs no library.