What do you know about the ninja?

From what I know, which is very little, ninjas were assassins of feudal Japan, usually hired as mercenaries from the lower classes. What you see in most movies is bullshit, as ninjas concentrated on not being seen and accomplishing a goal, like murder or spying, and what combat methods they knew were meant for escaping and defending. Wikipedia also says that shinobi is the proper word, rather than ’‘ninja’’, at least in Japan.
What do you know? Also, as a side question, do you think the ninja are still active?