Interesting, I've seen a lot of definitions for a startup now, but none of them really seem to grasp the core of it. Startups have repeatable business models, large growth rates, but Amazon is that and it's not a startup anymore. I like the above description that a startup still is confused about its product, customers and how to make money.

So what about Uber, Airbnb, Dropbox then for instance? For me Airbnb and Dropbox are definitely startups still, however Uber not anymore, even though they have similar size.

Why is that, is it the culture, where flat hierarchies are combined with high-growth rates? This is not the case with Google, definitely not Amazon, Apple, Facebook anymore, however, it is the case with Dropbox with 979 employees and AirBnb with 1,876 employees. Uber has 2,625 employees, are they already out of the startup size that is maybe 2,000 employees?