HDR10 is the baseline HDR format — the one every HDR-capable TV, console, Blu-ray player and major streaming service supports. It's open and royalty-free, meaning no licensing fees to producers or device makers, which is why it became the universal HDR floor. If a screen says "HDR", that practically always includes HDR10.
Technically, HDR10 is bt2020 colour space + 10-bit depth + the pq brightness curve + a single set of static metadata describing the brightest pixel in the whole file (MaxCLL) and the brightest average frame (MaxFALL). "Static" is the key word: those numbers are fixed for the entire movie. The TV uses them once to decide its tone-mapping strategy, then applies the same strategy from start to finish — fine for most content, but a problem when a film has both a very dark scene at night and an explosion in broad daylight; the TV can't optimise both.
HDR10's competitors solve that with dynamic metadata that changes scene by scene: hdr10-plus does it royalty-free, dolby-vision does it under licence with up to 12-bit colour. In practice, modern streaming services author HDR content in Dolby Vision (or HDR10+) and automatically fall back to HDR10 on devices that can't handle the more advanced format — meaning HDR10 is the "always works" version that anchors the whole HDR delivery story.
