The critical importance of white space in the effective delivery of visual content is well supported by this report comparing the reading performance of four different white space layouts. "Margins surrounding the text and leading (space between lines) were manipulated to generate the four white space conditions. Results show that the use of margins affected both reading speed and comprehension in that participants read the Margin text slower, but comprehended more than the No Margin text. Participants were also generally more satisfied with the text with margins. Leading was not shown to impact reading performance but did influence overall user preference. ...The use of white space for online reading is important as the number of people using online textbooks and materials continues to grow at a steady rate. ...Designers should be aware of the potential influence of white space on reading performance."