Batman is a fictional comic books/TV/video game super hero character created by DC. Unlike other super heroes, he doesn't have super powers. Instead, Batman uses his genius-level intellect, supreme physical athleticism, knowledge of almost every martial art known to man, mastery of acrobat, detective, strategist, tactician, escapologist, use of high-tech weapons, equipment, gadgets, mastery of stealth and disguise, photographic memory and being a expert marksman has lead to him being a famous crime-fighting hero in the fictional town of Gotham city. He has had many nick-names such as "the Dark night" and "the world's greatest detective".
Batman's secret identity is a very rich man named Bruce Wayne, a guy who lost his parents to a mugger and inherited all of their money. Bruce has his own butler named Alfred, one of the very few people who knows about his secret life as Batman.
Batman's has many enemies too. All of them, of course, are villains. The most commons ones are the Joker (a psychopathic clown-like criminal), the penguin (a devious crime-boss who is seldom seen without one of his trick-umbrellas, and performs crimes based on birds and uses his nightclub, the Iceberg Lounge, as a front for his criminal activities), Catwoman, Poison Ivy, mr. Freeze and ALOT more.
Batman first appeared in the detective comics in 1940. But because he was so popular, his own comic book series came out featuring him as a super hero.