It is fast because it is created on the Chrome JavaScript engine, which makes its library faster in executing code.
It is Asynchronous because it never waits for an API to give back data.
It is scalable because of its event mechanism, which enables the server to respond in a non-blocking way.
It is an open-source, offering an incredible open-source community, which has created some fantastic modules which added more power to Node.js apps.
Node.js never buffers data because the output is in chunks.