Font selection is one of the three parts of interface design, alongside layout selection and colour selection. It means choosing the style, size and spacing of the text on a screen so that everything is easy to read.
A readable font has plain, simple letter shapes and even spacing between the letters. Decorative fonts (curly, handwritten or very thin styles) may look eye-catching on a poster, but on a screen they slow readers down and reduce accessibility.
For example, imagine a school library page that lists book titles in a curly script font. You have to study every word for a moment before you can work out what it says, so finding one title takes far longer than it should. The same list in a plain font can be scanned in seconds, and it is easier for a reader with a visual impairment or dyslexia as well.
A screen should use only a small number of fonts, usually one for headings and one for body text. Every extra font adds another style for your eye to adjust to, so the page looks busy and is harder to follow. Sticking to a couple of fonts makes a site look tidy and helps users recognise which text is a heading and which is ordinary content, even on a page they have not seen before.
Text needs to be large enough to read comfortably from the distance the user is actually sitting at, and the lines should not be squeezed so tightly together that the eye loses its place. Designers should also avoid hyphenating a word across two lines, because the reader has to rebuild the word in their head before they can recognise it.
The right size depends on where the text is used. A departure board in a station entrance is read from several metres away, so it needs much larger letters than a short label next to a form field that the user is reading up close. On a website, the user's browser or device settings change the font size, so this is not something an accessibility feature has to do; zoom and magnification are.
Pearson BTEC Digital Information Technology · Accessibility