What is Terrorism?

One reader, Duffy, offers this definition. What do you think?

Terrorism is the application of violence on civilians or other non-combatants to achieve a political or ideological aim. It is both a strategy and a tactic. Strategically, a terrorist wants to attack the populace in hopes of the state cracking down so hard on the populace that they engender popular support for their cause. Tactically, it's bombing a nightclub full of civilians to kill them and terrorize everyone else.