How can you define a readable program?

A program that is easy to read & understand also easy to maintain and enhance. Readability is the ease in that text can be read and understood. Several factors to measure readability have been used, like as "speed of perception," "perceptibility at a distance," "perceptibility in peripheral vision," "visibility," "the reflex blink method," "rate of work" (e.g., speed of reading), "eye movements," and "fatigue within reading.