Dieter Rams (b. 1932) was chief designer at Braun through the 1960s–90s, shaping radios, calculators, and razors around the conviction that "less, but better" ("Weniger, aber besser") could be a working method, not just a slogan. Looking back on his own practice, he wrote down ten criteria for judging "is this good design?" — what's now widely cited as Dieter Rams' Ten Principles of Good Design.
The ten aren't ten independent boxes to check so much as ten angles on the same handful of concerns — "makes a product understandable" and "is unobtrusive" both aim at letting someone use a thing without fighting it; "thorough down to the last detail" and "honest" both insist that finishing touches shouldn't misrepresent the real materials or performance underneath. The tenth, "as little design as possible," works almost like a conclusion: even after a design passes the other nine, it asks whether there's still something left to remove.
The ten principles are widely credited with shaping the industrial design language of later electronics brands — Apple's design language most famously — and they translate directly onto digital products too: is it understandable, does it carry unnecessary ornament, does it hold up to years of daily use.
When to use
When auditing a product — or a screen — against the question "is this actually good design?"