By things they've made, either in the past, or the project they're applying with.

Thanks. Maybe it was lost in translation, but by Design do you mean appearance (like in graphical, interface, industrial design) or architecture (like operating system design)?

If it's the former, I hope you don't get offended by it, but I think, looking at HN and your website, that you wouldn't be accepted. :) Nor would Sergey and Page.

Both. They're the same thing.

Good design doesn't mean fancy design. Quite the opposite.

I also didn't mean fancy design.

But in your 'startup ideas', in the idea #16, you said Google has no sense of design, so I suppose that the people responsible for it (Google founders originally. Marissa Meyer with a team of designer now days, I believe) wouldn't be accepted in YC.

And that is more of a rhetoric observation. I know they would.

But then isn't the 'sense of design' requirement unnecessary?

Paradoxically, early Google both had no sense of (visual) design and yet managed to produce results that are way above average. The reason was that (perhaps knowing they weren't good at visual things) they just kept everything as simple as possible. It was like the design equivalent of a low-fee index fund, which despite not even pretending to know how to pick stocks, consistently generates above average net returns because of the low fees.