Consistently 4-B in the comics. Outliers go to 3-A to Low 2-C. In AiM, he seems to be weakened, trying to recover his strength as he sits at 5-A, though he can push his limits if the situation calls for it.
Superman is nearly unanimously recognized as the world's first superhero. Sporting his iconic "S", red cape and blue tights, the Man of Steel's outfit has changed over the decades through alternate universes and comic reboots. His appearance is a symbol of fear to evildoers yet an inspiration of hope to all who are good.
- "You have given them an ideal to aspire to, embodied their highest aspirations. They will race, and stumble, and crawl... and curse... and finally... they will join you in the sun, Kal-El."
- —Jor-El, in the non-canon All-Star Superman comic
Raised by kind, loving parents, Jonathan and Martha Kent, they instilled in him compassion, hope and the important ideal of helping someone because it is the right thing to do. As the Last Son of Krypton, he wants to live up to his alien heritage while, at the same time, embodying the best that humanity can be. While being able to be perceived as a larger than life character, he still has a human side by what he considers his true identity, Clark Kent. He himself, is a caring father to Jon Kent (Superboy) and great husband to Lois Lane. An inspiration to young and old alike, he is the world's greatest superhero.
Superman's father, Jor-El, had predicted the destruction of their homeworld called Krypton. With not much time, he desperately sent Kal-El, his son on a spaceship to travel to a habitable planet known as Earth, where its yellow sun would grant him incredible powers there. He was, presumably, Krypton's last hope. Being taken in by a kindly couple, Kal-El was named "Clark Kent"! He discovered his powers developing at a young age and while it was confusing at first, his adopted parents taught him to use them for good. Moving to the bustling city of Metropolis as a reporter, he would change into his alter-ego, Superman, to fight crime and super-villains alike. He would go on countless adventures with other heroes such as Batman and Wonder Woman, and be one of the founding members of the Justice League, an organized group of super heroes doing good across the planet and universe. During one of these adventures, he was teleported mid-flight by a source unknown to even him.
Dazed and weary, he surveyed his surroundings. That was surprising - he actually felt sore from that trip. He seemed to have landed in a forest, stranded in a crater. Looking around, he found the closest sign of civilization and talked to the inhabitants, even getting to know where he was and finding out that there were "heroes" here. The place was called Baile Ore and he soon got to befriend the heroes, and even decided to join in on their adventures. It was a beautiful town with not too few or too many people. Some notable friends he made, both as Superman and Clark Kent were Heat Man, Cun, Tundra, Ceelis, Note, Asura -- and plenty more. While pondering the means as to how he arrived in this place, he soon figured out he wasn't in the same universe as he saw significant differences started to show up, such as the disappearance of the JL Watchtower. Unfortunately, he found out that even his villains could arrive through random means, as he fought against Doomsday twice to brutal ends. It was also at this point that he realized he wasn't just weakened temporarily -- something must have happened to him, as he seemed more sluggish each day he spends here. With no room to relax or ponder about these things, Baile Ore was destroyed through the events of the build up, day of, and aftermath of Reckoning Day. They had to move to the Emerald Isles, where they currently are, dealing with even more comical hiccups.
Superman is Kryptonian. Their biology reacts to radiation from a yellow star, blue star, quasars, supernovas and interstellar radiation in general. However, Kryptonians never were fully exposed to these stars as they abandoned their space exploration posts and stayed under Krypton's red sun, which gave off dimmer and weaker radiation for them to absorb, rendering them powerless. Under Earth's yellow sun, Kal-El developed incredible strength and power by storing solar energy cells through hyper-metabolism over the course of years. He can expel his solar energy in a variety of ways. Superman has full control over his powers and senses. This explains why he can live in everyday life - otherwise he wouldn't be able to use a doorknob, and he would spend hours listening to one person's sentence if he can perceive things at speeds faster than light. His powers were honed and refined through repetitive use and training, though it was painful at first.
Superhuman Physical Characteristics
Super Hearing: Can hear across space somehow, even up to 25 light years away
Super Vision: Can focus to a sub-atomic level or planetary scale. Synonym for telescopic/microscopic vision
Heat Vision: Can cover the whole Earth or be used like a scalpel. Can match the sun in temperature, or be used to lobotomize someone through their pupils
X-Ray Vision: Can see through everything but lead
Limited Space-Time Manipulation: Can open and close holes in the fabric of Space-Time
Stellar Radiation Absorption
Energy Absorption: Capable of converting biological energy into solar energy
Resistance to Reality Warping: Resists Mr Mxyzptlk's universe without physics or gravity and his attempt to erase Superman from reality and memory
Resistance to Energy Manipulation
Resistance to Soul Manipulation
Resistance to Mind Manipulation: Can access his inner consciousness and astral plane to build up psychic blocks and fight off telepathic attacks
Resistance to Illusions
Resistance to Empathic Manipulation
Resistance to Matter Manipulation: Has survived sub-atomic destruction
Resistance to Time Manipulation
Resistance to Time Stop
Resistance to Existence Erasure: Withstands Darkseid's Omega Beams
Bio-Electric Aura: With his powers, his own personal force field is always around him, which allows him and his outfit to be left relatively unscathed. However, it can be depleted over the course of a battle and if he doesn't have much solar energy left, be hurt more easily. That's how he died to Doomsday.
Can use his abilities in a multitude of ways. While popularly portrayed as a "classic brute with no martial skill", he has been trained by Batman, Wonder Woman and Mongul personally. He is also strong enough on his own when he's powerless -- story arcs have shown him without powers causing cracks in walls and being as agile as a street-tier superhero. He is an expert in the pressure point arts which he uses with his X-ray vision to find the weaknesses of his enemies, and knows Torquasm-Vo/Rao to defend against psychic attacks. It is true that his most used style is to bull-rush the opponent and mix in some boxing, rarely using kicks, but don't underestimate him when he uses his powers, martial arts and psychic abilities in tandem with one another.
Kryptonite: Various versions of it exist, but the most popular, Green Kryptonite, slowly drains his powers and replicates the effect of poison on a Kryptonian. However, this method hasn't been effective in years and requires a sufficient or concentrated amount of it.
Red Sun Radiation: Being under a red sun can slowly weaken his powers, but he has never shown to have his powers fully disappear unless he literally dips inside one. Enemies have used red sun radiation to try and weaken the Man of Steel, and it's not bad of an option.
Magic: Superman has no special resistance to magic. Its effect on him seems to be complex and varies, as one time he was hit directly by the Claw of Horus, a magic-based gauntlet that hits with the force of a planet, but got up completely fine. To put it simply, we can speculate that Superman's durability would be a tad weaker than usual against magic-users.
Superman, if portrayed accurately, *cough* MoS *cough* actually cares about the civilians around him. He faces down bloodthirsty villains on a daily basis, and them trading blows often causes mayhem and tons of destruction. However, he will do his utmost best to try and mitigate the damage and loss of innocent lives. He is also always keen on holding back as to not kill his enemies, which gives him a disadvantage as he may start getting serious when it's too late.