What is the difference between a DDoS stresser and a botnet, and how are they related?

A DDoS stresser is a tool or program used to launch a DDoS attack, while a botnet is a network of compromised computers (bots) controlled by a malicious actor. Stressers often utilize botnets to generate the attack traffic. The botnet operator provides access to the resources to be used to create the attack.