Texel density
How many texture texels cover a given area of the world — the measure of how uniformly detailed surfaces appear.
If one wall is razor-sharp and the next is blurry, it's usually because they have different texel density: the number of texels per metre of surface, or per pixel on screen. Keeping it consistent across assets is fundamental to a coherent look, and it drives both UV scaling and how large a texture needs to be. Too low and the surface turns mushy; too high and you waste memory while the surface starts to shimmer at a distance — exactly what mipmapping and anisotropic filtering exist to tame. Many tools display density as a checker pattern so artists can compare objects against each other.