12-bit means each colour component of a pixel can take 4096 distinct values, compared to 1024 in 10-bit and 256 in 8-bit. That's around 68 billion possible colours per pixel — far more than the human eye can distinguish. The practical effect: even the smoothest possible gradient, viewed on the best possible display, won't show any visible stair-stepping or banding.
In real life, 12-bit lives in two places. First, Dolby Vision — the premium HDR format used by Netflix, Apple TV+, Disney+ and most flagship streaming services — supports up to 12-bit colour as part of its specification. In practice most Dolby Vision content is mastered in 12-bit and delivered as 10-bit, because no consumer display actually shows the difference, but the 12-bit master gives the format headroom for future displays. Second, professional production codecs — ProRes 4444 XQ, DNxHR HQX, FFV1 — store 12-bit to avoid any quality loss during multiple rounds of editing, colour grading and VFX work.
For a product team, 12-bit is almost always a mastering and archival concern, not a delivery one. You'd produce or store in 12-bit to keep your future options open, but the file that ships to a viewer's TV is virtually always 10-bit. The exception is theatrical Dolby Cinema and the most demanding broadcast contribution, where 12-bit delivery is the norm. If you're not in those very narrow segments, 10-bit is the right delivery answer and 12-bit is overkill that just inflates your bandwidth costs.
