Just what IS terrorism?

terrorists are people who attack the people who write the history books.but then look at how we view the crusaders (or at least did until a few years ago when it became cool to hate anything christian). they massacred a huge number of muslims at a battle in the 12th century on september 11th (i can't remember the year). funny thing.but we write our history books so we view ourselves as the victim and champion in everything.