Pac-Man is-well, hard to explain. He's a yellow ball that eats yellow dots while fighting enemies such as ghosts. His powers range from eating stuff to launching energy balls to...head-butts?
He was one of the first videogaming icons, being well before Mario an acclaimed "hero"
There are two different Pac-Mans, the Pac-Man World one and the Pac-Man and the Ghostly Adventures one, the one in this page is the first one.