CCT follows blackbody radiation — the same physics that makes a heated object glow from red through white to blue as it gets hotter. LEDs recreate this by blending chips: dual-channel fixtures mix a 2700K and a 6500K LED to glide across the range, multi-channel RGBW fixtures trace the Planckian locus directly, and simpler fixtures use an on-board switch to lock in a fixed blend. Tight colour binning (measured in MacAdam ellipse / SDCM steps) keeps fixtures from the same batch looking consistent side by side — 3-step is the usual bar for architectural work.