A texel is a term for any point in a
bitmap texture. It is short for a
texture element, just as
pixel is short for a
picture element. Hence a
bitmap texture consists of a two-dimensional
array of texels. It does not have anything to do directly with the display.
Why is this concept useful? Well, it can get very confusing for people in computer graphics when they discuss the application of textures to polygons and other objects -- in the process commonly called texture mapping; because one pixel in a polygon can correspond to several texels in the texture, or vice versa. With the word texel, one can say something like: "In this case, four texels map to one pixel." Without the word texel, one would be obliged to say something horrendously verbose like: "In this case, four pixels in the texture image are mapped to one pixel on the graphical display".