Character and word recognition are more easily achieved with upper- and lowercase letters, since they create a greater range of word-icon shapes and individuality than uppercase alone. Capital letters all appear to occupy equal spaces when set in a line of text, so the words they form arc more difficult to discern at a normal reading speed. The relative weight of type can also affect legibility. Medium weights are easiest to read because of the visual balance between the counter-shapes and letterstrokes. Extreme weights of both light and bold type are more difficult and tiring to read as the contrast between the letterstrokes and counter-shapes is distracting.