Origins
Artist Bob Kane is generally credited with creating Batman, though writer Bill Finger deserves a share of the credit was well. The character first appeared in the pages of Detective Comics No. 27, in which he was depicted as a blend of noir detective and pulp action hero. He operated under the guise of millionaire Bruce Wayne, who (as was revealed in later adventures) was driven to fight crime after witnessing the death of his parents as a child. In order to frighten evildoers, he dressed in a weird and menacing costume patterned after a bat. He used his vast fortune to create an array of crimefighting gadgets, including a utility belt full of detecting gear and (later) his famous car, the Batmobile. The character was an instant hit and earned his own comic-book line within a year.
Lightening Up
Though he was originally conceived as a grim avenger of the night, a number of forces soon drove Batman in a much lighter direction. A sidekick, Robin the Boy Wonder, was introduced in 1940, providing not only a brighter look to the comics but a surrogate son for Batman to look after. Public backlash against dark and gory comics in the 1950s led to further changes, and Batman started to battle outlandish figures like space aliens and magical creatures (which were considered more kid-friendly) as often as criminals from the mean streets. The trend came to a head in 1966, when a campy television version of Batman starring Adam West became a huge hit. The comics received a shot in the arm from the show, and quickly came to reflect its comedic, tongue-in-cheek tone.
A Darker Tone
When the show faded in popularity, however, so too did the comics. As the 1960s drew to a close, the publishers believed that a change in overall tone was in order. Writer Denny O'Neil and artist Neal Adams spearheaded that trend, taking the Batman comics away from camp silliness and back to the dark, hard-edged roots of Kane and Finger. The trend has continued to the present day, but reached its heyday in the 1980s, when a pair of Batman graphic novels--Frank Miller's "The Dark Knight Returns" and Alan Moore's and Brian Bolland's "The Killing Joke"--were hailed as breakthroughs for the medium.
Movies and Modern Comics
Tim Burton's 1989 film adaptation of the character proved to be a huge hit, which put comic sales at record levels and introduced a whole new generation to the character. A subsequent animated series in the early 1990s earned both popular and critical acclaim, helping to push Batman further to the forefront of the medium. The '90s proved to be a boom period for the comics industry, and while sales dipped in the early part of the 21st century as economic doldrums took their toll, the unprecedented critical and commercial success of another Batman movie--Christopher Nolan's "The Dark Knight"--helped keep the character fixed firmly in the public eye.
Types
As of this writing, there are six comic book titles that use Batman as a principal character. The big two are his "core" books, Detective Comics and Batman. The other four are Batman/Superman (covering his adventures with the Man of Steel), Batman Confidential, All-Star Batman and Robin the Boy Wonder, and Batman and the Outsiders, in which he leads a team of misfit superheroes. Batman also makes cameo appearances in other heroes' books, and has a recurring role in "team" comic titles like Justice League of America and The Brave and the Bold. Many of Batman's supporting characters have their own titles too. Robin and Nightwing--his current and former sidekicks, respectively--have books recounting their solo adventures, as does his nemesis/paramour, Catwoman. Barbara Gordon, the original Batgirl, also appears in a team comic entitled Birds of Prey.