Readability is the ease with which a reader can understand a written text. The readability of a particular text depends on content (for example, the complexity of its vocabulary and syntax) and  typography (for example, its font size, line height, and line length). Researchers have used various factors to measure readability, such as

• Speed of perception
• Perceptibility at a distance
• Perceptibility in peripheral vision
• Visibility
• Reflex blink technique
• Rate of work (e.g., reading speed)
• Eye movements
• Fatigue in reading