Photomontage

I went to a site called "www.photomontage.com".
I was told to go there, look at a few pictures and try to figure what photomontage meant.
I just think that photomontage is like pictures or videos put together by someone, such as animations, and etc.
I saw a small box with six pictures of people, and one of the pictures had a man's face in it and it'd go darker and then back to normal, there was also a picture of a woman and her face kept moving to the left and to the right too, in a very quick motion.
It was very interesting to see pictures like that.