A channel dedicated to representing how opaque a given pixel is. Unlike the red, green, and blue channels, which specify the intensity of their respective colors, the alpha channel specifies the opacity of the entire pixel. For example, if a pixel was defined using float values ranging from 0.0 to 1.0, an alpha channel intensity of 1.0 would indicate 100% opacity, and an intensity of 0.0 would indicate 0% opacity, or transparent.