Legibility and Readability
Legibility and readability are very important concepts in typography, and the two are often confused.
Legibility is a measure of how easy it is to distinguish one letter from another in a particular typeface. Usually it’s primarily the concern of the typeface designer, who should ensure that each individual character or glyph is unambiguous and distinguishable from all others in the font. Legibility is also about choosing the right typeface at the right size.
Readability can be defined not on a letter-by-letter basis, but by how the combinations of letters are read within a larger body of text. In other words, readability is defined by how easy it is to read words, phrases, or blocks of copy such as a book, a web page, or an article.
Legibility refers to perception; readability refers to comprehension. They both are determined by font choice, sizing, spacing, and text alignment.
[fig.1]When reaching the end of the line on the top paragraph, it is easier to identify the correct next line in the preceding text. The paragraph below causes some difficulty in finding the next line even though the letters themselves are easier to understand. The first block of text demonstrates readable type, while the second shows legible type.