Comic featuring Superman's debut sells for record-breaking $6 million

It's a bird! It's a plane! It's the most valuable comic book in the world!A copy of the comic book that introduced the iconic Superman to the world became the world's most expensive comic book when it sold for $6 million at an auction.According to Heritage Auctions, a copy of Action Comics No. 1, the 1938 comic book featuring the first appearance of Superman, sold for $6 million at an auction on Thursday.The previous auction record was held by the CGC Near Mint+ 9.6 copy of Amazing Fantasy&