A denial of service (DoS) attack is a cyberwarfare tactic that usually involves bombarding a computer resource with so many requests that it can’t handle them all. In the case of a web attack, the server either crashes or simply spends so much of its time responding to the bogus requests that legitimate ones are not handled or handled so slowly that the site seems unavailable.
In the recent dissident uprising in Iran, a DoS attack was conducted by everyday people who wanted to silence the Iranian government’s lies about what was going on. A programmer in the United States wrote some code that would request refreshes of the key Iranian government web sites every second. People all over could go to the programmer’s proxy and click “start” to conduct an additional attack. It caught on and many of the “official” Iranian sites were effectively shut down: a seeming victory for the forces of freedom.
Unfortunately, as vast and infinite as the Internet seems, you always eventually run into scarcity in one form or another. In this case, dissidents in Iran started pleading with the world to stop the DoS attack because it was depriving them of the bandwidth they needed to get their own message out to the world. In other words, the people the DoS perpetrators were supposed to be helping were actually also hurt by the attack.
I strongly believe that clogging up the Internet (with spam or bogus requests) is wrong no matter how noble your intentions may be.