Comic book collecting is a hobby that treats comic books and related items as collectibles or artwork to be sought after and preserved. Though considerably more recent than the collecting of postage stamps (philately) or books (bibliophilia), it has a major following around the world today and is partially responsible for the increased interest in comics after the temporary slump experienced during the 1980s. Overview Comics are collected for several possible reasons, including appreciation, nostalgia, financial profit, and completion of the collection. The comic book came to light in the pop culture arena in the 1930s due to the popularity of superhero characters Superman, Batman, and Captain Marvel. Since the 1960s, two publishers have dominated the American comic book industry: Marvel Comics, publisher of such comics as Spider-Man, X-Men, and Fantastic Four, and DC Comics, which publishes titles such as Superman, Batman, and Wonder Woman. Other large non-manga publishers include Image Comics, IDW, Valiant Comics, and Dark Horse Comics. As comic books regained their popularity in the 1960s during the boom of the Silver Age, fans organized comic book conventions, where they could meet to discuss their favorite comics with each other and eventually with the creators themselves. , numerous conventions and festivals are held around the world, with Comic-Con International, held annually in San Diego, being the largest and best-known convention in the United States. While some people collect comic books for personal interest in the medium or characters, others prefer to collect for profit. To assist both types of comic book collector, comic book price guides are available and provide estimates of comic book values as well as information on comic book creators and characters. The price guides assign values for comic books based on demand, availability, and the copy's condition. The longest running price guide is the annual Overstreet Price Guide, first published in 1970. Another current monthly price guide is Comics Buyer's Guide. The growth of the Internet in the late 1990s saw development of online databases to track creator, character appearances, and storylines, as well as websites combining comic book price guides with personalized collection tracking to provide collection values in real-time. The Grand Comics Database is a popular online resource for comic book creator and character information. Popular online price guide and collection tracking services include comicbookrealm.com, comicspriceguide.com, and GPAnalysis. The increased popularity of online auctioning services like eBay or Heritage Auctions for buying