When?
Always!
How?
There are two important aspects to achieving success with simplicity:
- Remove unnecessary components, without sacrificing effectiveness.
- Try out alternative solutions that achieve the same result more simply.
Whenever you're designing, take it as a discipline consciously to remove all unnecessary visual elements.
Concentrate particularly on areas of the layout that are less relevant to the purpose of a page, because visual activity in these areas will distract attention from the key content and navigation.
Use visual detail - whether lines, words, shapes, colour - to communicate the relevant information, not just to decorate.
Here's an example of a design that suffers from not enough simplicity.
Yaxay's interface uses a lot of pixels, but the vast majority of them are decorative, part of the page background. Relatively few pixels are used to user to find or understand information or interact with the site.
See how much "stuff" there is to look at, and notice how few of the pixels are used to clarify actual navigation, actual content, or actual interactive features.
Edward Tufte is the boss when it comes to the design of information. He uses the terms "data ink" (i.e. detail that enables information transfer) and "non-data ink" (i.e. detail that's just detail) to describe this phenomenon.
One way Tufte specifically measures the effectiveness of information design (graphs, charts, presentations etc.) is using the ratio of data-ink to non-data-ink. The higher the proportion of data-ink used, the more likely it is that a design is effective.
Taking the Yaxay detail above, there's a lot of what I call "busyness", i.e. a lot of edges, tonal changes, colour variations, shapes, lines... a lot of stuff to look at. But, in this detail, the only useful features are:
- The site logo, and
- the label on the nav button (which reads "art gallery")
All the rest of the "busyness": the shapes in the background, the diagonal lines in the interface panel, the grid, the gradients... all this is noise, it's all "non-data ink", because it's not enabling communication.
