Superman is one of the most well-known fictional characters in history, rivaled only perhaps by the likes of Mickey Mouse and Sherlock Holmes. His powers make him quite literally invincible on Earth, which is why he's from another planet in the stories. Superman is Kal-el from the planet Krypton, son of Russell Crowe-- I mean Jor-el. So I've done some research regarding Clark Kent, and there are some interesting explanations as to why his powers work the way they do.
Beginning with the obvious of the bunch, Superman's strength. The idea behind Superman's strength is that he came from a planet that had a stronger gravity than Earth's, so his muscles are naturally used to being strained by that gravity. It's claimed that the gravity on Krypton would have to be at -least- fifteen times that of Earth. Which means that since Superman weighs around 225 lbs (which is about the same that I weigh, and Superman is only an inch taller than I am at six feet four inches), he would weigh 3375 lbs or over one and a half tons on the planet Krypton. Since Superman and I are pretty close in height and weight, I figure I should point out the fact that he appears to be all muscle and no fat, which isn't the case for me, This seems to create a discrepancy between Superman's height and weight. Two hundred and twenty five pounds seems rather light to me for a Man of Steel, who appears almost like a body builder. It seems to me he'd be at least 250 to 275 lbs, but that's a minor detail. What I'd like to point out as a major flaw in Superman's story is that, yes he was born on Krypton and his body was probably used to the gravitational pull for a while, but he lived out most of his life on Earth, where his body should have become acclimated to Earth's gravity. Or, if he did manage to keep the same physique he had on Krypton, he would have to exercise constantly in order to maintain it just like Astronauts have to exercise on the International Space Station so that they do not experience muscular atrophy.
Superman's ability to flight is supposedly attributed to the fact that the civilization on the planet Krypton is millions of years ahead of Earth, and their bodies have reached evolutionary perfection. Since Superman is powered by the Sun, he can alter his own gravitational field with the energy he gathers and propel himself into the air any time he likes. Don't ask me how that works, I don't know.
The next ability is actually the most likely to make sense. Not so much as to how he has the ability, but more on how it works. The famous X-ray vision that young men dream about having. X-rays are outside of the visible spectrum and pass through your body all the time. Superman can see in this spectrum and look through buildings, clothes, people, skin, and all manner of other things except lead and other dense metals like Gold. In a similar fashion to being able to see in the X-ray spectrum, Superman can also see and utilize the Infrared spectrum to create heat and melt objects. Why they're shown as lasers is beyond me.
Source: SUPERMAN'S Secrets Exposed.