Starting in 1985 with the famous Crisis On Infinite Earths DC has had many large scale crossovers in their multiverse that retconned large parts of continuity, reaching a peak in the late 2000's when they had three major retcon crossovers starting in 2005 and finishing in 2011 (with possibly more to come). Good job on messing up your continuity so much DC.
One funny thing about DC Comics is that it's not the original company name and the "DC" was taken from one of the more popular (and still ongoing) lines called Detective Comics, which is the comic that introduced Batman. This means technically the full name is Detective Comics Comics.
Person 2: Ugh. I love DC. It has great characters. But they have too many big retcons. I wish they'd just be stricter on maintaining continuity. Is it any wonder why so many people who want to get into comics feel intimidated and don't know where to start?