Denial of Service (Dos) and Distributed Denial of Service (DDoS) attacks are unforgiving. They test the limits of your web server and application resources by sending spikes of fake traffic to your website. It is also notoriously difficult to conduct forensics on a DDoS attack, making the source of the attack a mystery.
DDoS attacks are getting cheaper, more sophisticated and more readily accessible every day. As a result, they have become an instrument of war for both commercial and political purposes.