"Distributed denial of service attack" may be organized by one person. Its definition?

Is it true that nobody has ever been able to mount a successful distributed denial of service attack?

Even if a "distributed denial of service attack" has many moving parts, it may be orchestrated by a single individual. What is it?

What is the distinction between denial-of-service and distributed denial-of-service attacks? Which is the most hazardous? Why?

What is a denial-of-service (DoS) attack? Why does a distributed denial of service (DDoS) attack pose a more serious threat? Describe the three countermeasures against a distributed denial of service attack.

Allow me to describe distributed denial-of-service attacks in the event that you are not acquainted with them.

A distributed denial-of-service attack is impossible for a single individual to pull off, but what exactly is it?