Icons are pictorial representations of functions and objects, important not only for aesthetic reasons as part of the visual identity of a program, but also for utilitarian reasons as shorthand for conveying meaning that users perceive almost instantaneously. Well-designed icons improve the visual communication and strongly impact users' overall impression of visual design. Last but not least, icons are space-saving and improve usability by making programs, objects, and actions easier to identify, learn. Icon use should be consistent throughout the interface.
- Design icons with a small number of metaphors .
- Apply metaphors only once (e.g. do not use a brush twice for different options).
- Rethink conventionally used metaphors (e.g. the clipboard icon of paste).
- Antiquated metaphors might work well (e.g. a floppy is not necessarily outdated to represent save).
- Adjust the degree of abstractness according to familiarity of the metaphor.
- Use arrows only if they can easily be related to spatial features such as Previous/Next in a sequence or Up/Down in a hierarchy. Avoid using arrows metaphorically (such as for Reply/Forward or Undo/Redo).
- Attempt to use metaphors that are independent of language and culture.
- Make icons simple.
- If an icon has important details at larger sizes, rather than simply scaling it down, create unique versions of the icon at smaller sizes. Critical details may become unrecognizable when scaled down.
- Avoid using text in icon designs; it may not scale well to smaller sizes.
- Icons of a similar type share a consistent visual language (mimetypes, folders, devices, etc.).
- Test your icon set on strength of association, discriminatory power, conspicuousness, and, if applicable, on accessibility.
- Used for application toolbar actions, menus, and status and notifications. Also used for small (16x16) devices and places icons (folders, usb drives, etc.).
- Rely on a distinct shapes instead of fine details to distinguish between them.
- Color can be used for distinction (change of state, destructive actions, etc.).
- Unique and easily recognizable.
- Have the widest variation of color and visual style to represent the visual identity of the application.
- When creating an system icon theme, respect trademarks by avoiding significant alterations to application icons.
- For standard actions (back forward, open, save, refresh, etc.) use an icon from the platform-provided set. The KDE Platform 4.x uses the Oxygen icon set. Ask at the kde-artists mailing list to request addition of a specific item.
- If you would like to request help designing icons unique to your application, you can ask for help on the KDE Visual Design Group Forum.