Most of us already hear of what is a DDOS attack. Distributed Denial of Service or commonly called as DDOS is a type of DOS attack where multiple compromised systems — which are usually infected with a Trojan — are used to target a single system causing a Denial of Service (DoS) attack. –http://www.webopedia.com/TERM/D/DDoS_attack.html
This is a video of VideoLan, creators of VLC, featured in Geek.com portraying how DDOS really works and how does it looks like.
As described in the video, videoLan experienced major DDOS attack on its infrastructures dealing 400 request per second and another 200 downloads of VLC per second, that is almost 30GBps.
note: image credit to technologybanker.com