The success of start-ups strongly depends on the ecosystem in which they are inserted. In this regard, it is important to understand the concept of the start-up ecosystem, especially from the point of view of scholars and professionals. The desire to deepen the dimensions and components of the ecosystem and to observe more closely the best start-up-friendly ecosystems, then propose a comparison with the Italian context, is derived from evidence indicating that the most successful start-ups are concentrated mainly in certain areas of the world, and this concentration is by no means accidental.