Typography

Limit the number of fonts and styles you use in your interface. As with too many colors, using too many fonts results in visual clutter. Use bold fonts sparingly. While bold text attracts attention, overusing it can distract the user and make it difficult

to focus on what is important. Limit its use to titles, headings and key items that should have the user’s attention. Similarly, limit your use of italic text. Used in isolation, italics may attract attention, but in general it can decrease the emphasis on the information and make the text less readable.

Sans serif fonts such as Arial are recommended for touch panel design due to their clean look and ease of readability (see Fig. 6.) For buttons and icon text with no accompanying icon, font sizes should be no smaller than 10 points up to a

maximum size of 42 points for large icon text such as a keypad. If a font is used to further define an icon, then the minimum size is 8 points. Headline and title bar text should typically be 14-16 points in size. Use a consistent font for common interface elements for visual consistency.

The wording you use in your interface is a primary form of communication with the user. Keep text in the user interface as brief as possible, usability studies indicate that users are more likely to read short blocks of text than long ones. Review your work to eliminate wordiness, and keep user interface text short without sacrificing clarity. Position the text so that any relationship with a particular control is clear. Use sentence-style capitalization and ending punctuation. Avoid using

abbreviations unless the abbreviated form is as familiar to users as the full word or phrase. You can use an acronym for a term that is not trademarked or for a well known industry standard. Instructional text helps reduce or eliminate confusion, use introductory text in dialog boxes to provide additional information. Providing clear direction in error messages is extremely important. When creating error messages for the interface, ensure that the message clearly communicates the next step a user should take. Also if a message opens in a pop-up, be sure to allow adequate time for the user to read and understand the message.