Iaido is a Japanese martial art related to drawing the sword, cuting the opponent, removing the blood from the blade and then puting the sword back into the scabbard. Several movements are practiced and they are not restricted to the afordmentioned ones. There are also several different different schools -- I practice Muso Jikiden Eishin Ryu at the Masamune dojo. My grade is currently nidan and I am a qualified coach.
Due to the nature of this martial art, only the movements (kata) are practiced against an imaginary opponent. In this way, a safe environment can be created for the practice.
Even though some people simply define Iaido as the art of drawing the sword, Iaido goes well beyond that, being a philosophy of life. For instance, a person who practices Iaido should be always seeking to improve him/herself, to be ready to deal with unexpected situations/sudden problems, to be humble and persistant.