DC Entertainment declared June 12 as Superman Day in 2013 to honor the creation of the world's most famous superhero, two days before the release of the movie "Man of Steel." The day was initially called “Man of Steel day” but later became “Superman Day.”

The company collaborated with booksellers and comic book retailers on the inaugural day to give out free copies of "All Star Superman #1 Special Edition" across the United States.

Writers Jerry Siegel and Joe Shuster created the legendary character in 1933 but Superman appeared only in 1938 after it was sold to Detective Comics. Superman was originally supposed to be featured as a bald telepathic villain bent on world domination. According to Shuster, the character was inspired by heroes such as Hercules and Flash Gordan, Superhero Etc reported.

An issue of Superman in which Lex Luthor attached him with a weapon called an atomic bomb was released when the U.S. was secretly experimenting with nuclear weapons. The government delayed the story’s publication due to the seriousness of the matter, OHfact reported.

When Superman debuted, he did not have any powers like flying. His only power was to just jump long distances. His more iconic powers started taking shape in the coming years. His x-ray vision was introduced in "Action Comics (Vol 1) #11" in 1939 and his ability to fly was created only in the 1940s.

Superman was presented as someone who can travel faster than light, which was not appreciated by Albert Einstein. The eminent physicist believed nothing could travel faster than light and this created a debate between him and Isaac Asimov, an American writer and professor of biochemistry.

The ‘S’ logo on Superman costume doesn’t actually stand for Superman. It represents "hope" and "hero." It also means "resurrection" when turned upside down.

Here are some quotes about Superman from Brainy Quotes.

1. “What makes Superman a hero is not that he has power, but that he has the wisdom and the maturity to use the power wisely. From an acting point of view, that's how I approached the part.” — Christopher Reeve

2. “I grew up watching 'Superman.' As a child, when I first learned to dive into a swimming pool, I wasn't diving, I was flying, like Superman. I used to dream of rescuing a girl I had a crush on from a playground bully.” — Tom Hiddleston

3. “When I first found out that Superman wasn't real, I was about maybe eight. And I was talking to my mother about it. And she was like, 'No, no, no. There's no Superman.' And I started crying. I really thought he was coming to rescue us. The chaos, the violence, the danger. No hero was coming.” — Geoffrey Canada

4."For a lot of people, Superman is and has always been America's hero. He stands for what we believe is the best within us: limitless strength tempered by compassion, that can bear adversity and emerge stronger on the other side. He stands for what we all feel we would like to be able to stand for, when standing is hardest." — J. Michael Straczynski.

5. “The first Superman film took up a huge chunk of our lives, but it was a wonderful time for us. We were young, my daughter was little, we were filming in London for a year, so we became like a close family.” — Margot Kidder