(updated May 7th 2004)
Detective Comics is the full name behind DC Comics. Admittedly, this means that when you say "DC Comics" you're really saying "detective comics comics" which doesn't make any sense. However, when you understand the history behind it, ...well okay maybe it still doesn't make sense but one understands why it happened that way.
What places Detective Comics in the history books is the fact that among other characters that were introduced in this publication, most of which are now lost to antiquity, this title featured the earliest works of Batman by that character's creator Bob Kane. Detective Comics also hosted other characters in the early days, but eventually Batman took over the entire book for every issue, even after getting his own self-titled comic. Along with Superman, Wonder Woman and a few others, Batman has for over sixty-five years been a major staple of success and fortune for DC Comics, Inc. During the company's fiftieth anniversary, the character of Batman was prominent in the maxi-series Crisis on Infinite Earths, and still delights audiences even today, through movies, television, and still the good old pulp comic book.
Back in 1937, a partnership of comic book publishers called Wheeler-Nicholson was forced to take on Harry Donenfield as a partner due to financial troubles. This was after The Great Depression and before World War Two so comic books didn't make a whole lot of money. And until now most comic books consisted of humorous comical characters -- hence the use of the word comic in the name. Granted, today comic books are not necessarily funny, but we call them comics anyway.
The new three-way partnership of Wheeler, Nicholson and Donnefield needed a new name. They planned to introduce their third title and call it Detective Comics, so for simplicity's sake, the new company name was christened Detective Comics Incorporated. Over time the name was eventually abbreviated to DC Comics. Today, DC is one of the two largest comic book publishing houses in America, now owned by Time-Warner, with at least a thousand copyrighted characters as financial commodities. By the way, Time-Warner used to be two different companies: Time Magazine and Warner Brothers. America On Line used to be in the mix there somewhere around the turn of the century, but I don't think anybody wants to talk about that anymore.
Detective Comics was first launched in March of 1937, over a year before they were to publish Action Comics #1 which is also a hallmark comic book title. Unlike previous titles, the material for Detective Comics was solely suspenseful crime stories intended to appeal to a wider audience base. By the end of 1937, Wheeler and Nicholson still had financial troubles, and were forced to sell the remaining ownership to Donnefield, who remained as president of the company until his death in 1965.
So, just like Mount Everest is the name of a mountain, or Wolf Brand Chili is the name of a brand of chili, Detective Comics is the name of a comic book that's been in publication for over half a century, and also the name of the comic book company that publishes it. Go figure.