Instead, I'm going to give you a meaty chunk from the middle and urge you to immediately go read the entire thing, please:
The point of terrorism is to cause terror, sometimes to further a political goal and sometimes out of sheer hatred. The people terrorists kill are not the targets; they are collateral damage. And blowing up planes, trains, markets or buses is not the goal; those are just tactics. The real targets of terrorism are the rest of us: the billions of us who are not killed but are terrorized because of the killing. The real point of terrorism is not the act itself, but our reaction to the act.Schneier on Security: What The Terrorists Want (August 24, 2006)
And we're doing exactly what the terrorists want.
We're all a little jumpy after the recent arrest of 23 terror suspects in Great Britain. The men were reportedly plotting a liquid-explosive attack on airplanes, and both the press and politicians have been trumpeting the story ever since.
In truth, it's doubtful that their plan would have succeeded; chemists have been debunking the idea since it became public. Certainly the suspects were a long way off from trying: None had bought airline tickets, and some didn't even have passports.
Regardless of the threat, from the would-be bombers' perspective, the explosives and planes were merely tactics. Their goal was to cause terror, and in that they've succeeded.