A denial-of-service attack (DoS attack) or distributed denial-of-service attack (DDoS attack) is an attempt to make a computer resource unavailable to its intended users. Although the means to carry out, motives for, and targets of a DoS attack may vary, it generally consists of the concerted efforts of a person or persons to prevent an Internet site or service from functioning efficiently or at all, temporarily or indefinitely


So basically you can Lag/Crash Games,  now thats just mean :(


Try and take down a website (requires more people, depending on how well the website is hosted)

Its a very basic program, it just sends huge amounts of ping requests to the server

Can send over 3 types of connections: HTTP, TCP, and UDP