Dieter Rams.

Dieter Rams' 10 principles to good design:

Good design:
Is innovative - Rams states that possibilities for innovation in design are unlikely to be exhausted since technological development is always offering new opportunities for innovative design. He also highlights that innovative design always develops in tandem with innovative technology and can never be an end in and of itself.

Makes a product useful - A product is bought to be used. It has to satisfy certain criteria, not only functional, but also psychological and aesthetic. Good design emphasises the usefulness of a product whilst disregarding anything that could possibly detract from it.

Is aesthetic - Only well-executed objects can be beautiful. The aesthetic quality of a product is integral to its usefulness because products used every day have an effect on people and their well-being.

Makes a product understandable - It clarifies the product’s structure. Better still, it can make the product clearly express its function by making use of the user's intuition. At best, it is self-explanatory.

Is unobtrusive - Products and their design should be both neutral and restrained, to leave room for the user’s self-expression. Products fulfilling a purpose are like tools and are neither decorative objects nor works of art.

Is honest - Honest design should not attempt to make a product seem more innovative, powerful or valuable than it really is. It should not attempt to manipulate the consumer with promises that cannot be kept.

Is long-lasting - It should avoid being fashionable and therefore never appears antiquated. Unlike fashionable design, it lasts many years – even when the trend may be in favor for disposable products.

Is thorough down to the last detail - Dieter Rams states that nothing must be arbitrary or left to chance in the design of a product since care and accuracy in the design process show respect towards the consumer.

Is environmentally friendly - Good design should make an important contribution to the preservation of the environment by conserving resources and minimizing physical and visual pollution throughout the lifecycle of the product.

Is as little design as possible - Dieter Rams makes the distinction between the common "Less is more" and his strongly advised "Less, but better" highlighting the fact that this approach focuses on the essential aspects thus, the products are not burdened with non-essentials. The desirable result would then be purer and simpler.

Thanks to Wikepedia.