What is GIF?

Thirty-five years old and still everywhere, because it does one thing nothing else quite does: animate inline, silently, in any context that displays an image. The cost is a 256-colour palette and no real motion compression, which makes GIF a poor way to store video and an excellent way to send a three-second loop.

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.