Legible type and readable type seem like synonyms, but typographically they are not the same thing.
Legibility refers to the recognition of individual letters and words, whilst readability is the clarity and speed at which content can be read and understood.
The legibility of a typeface is dependent on its design (and perversely some typefaces are deliberately designed to be illegible), whilst readability depends on the skill of the typographer in choosing a typeface and arranging the type well on the page.
One of the more common mistakes designers make is to choose a typeface designed for one purpose and use it for something else for which it is unsuitable. A classic example is the use of the display face Avant Garde as a text font. Equally, you would not use a difficult to read brush script for a fire exit sign where the meaning needs to be read and decoded quickly.
Since the introduction of the Disability Discrimination Act in the UK in 1995 and the Disability and Equality Act in 2010, typographic design needs to be inclusive of people with a wide range of visual impairments. Making sure that your type is structured to be legible and readable was always a hallmark of good design, but now it is a prerequisite.
In the next two posts I'm going to look at little deeper into some of the issues around the legibility and readability of type.
