Superpowers are imaginary abilities that superhuman characters have. Almost every superhero and villain has something that sets them apart from normal people. Though in many cases these are skills and abilities that many people can acquire (though with a level of expertise that separates them from most humans), superpowers are one of the most famous aspects of superheroes. These powers can come from a variety of sources (including magic, scientific augmentation, or mutation, to name a few) and can range from subtle (precognition, psychic empathy) to dynamic (super speed, super strength, super agility, flying) to overwhelmingly powerful (reality-bending) and everything in between.
Super Powers can be acquired in multiple ways.
Mutation refers to a change in the nucleotide sequence in the genome of an organism and in some cases can result in a drastic change in DNA. While in real life, a mutation usually simply refers to some form of deformity or physical irregularity, in superhero stories this can often result in superpowers and abilities far beyond those of normal humans. It's very common for a superheroes power to come from an accidental mutation, often from a science experiment gone awry and/or some form of genetic experimentation.
Though mutation in comics often means a normal human who is changed on a genetic level, in the Marvel Universe, it has a much more specific connotation. These mutants aren't the result of accidents, but rather is a result of a fluke genetic change unlike most other humans. In many cases, the powers don't manifest until puberty, though it is also common for some to develop powers earlier and occasionally, later in life. While heroes like Spider-Man and The Hulk the results of altered genetics, only mutants born with their specific powers, abilities, and/or deformities are considered mutants within this continuity, for the most part. Characters who aren't born mutants and are transformed in some capacity are referred to as "mutates", to set them apart.
Some powers are simply a form of magic acquired through intense study of ancient arts. These powers often consist of specific spells. The casters themselves are not necessarily different from others, rather they just have a knowledge that the normal populace does not. Usually, it involves them to understand either the magical forces that are a part of the universe or to be able to perform the rituals that invoke them. Often, these magics need to be accessed through words, symbols, gestures, sacrifice, invocation of a higher deity or other entity or reading a spell, though there are other ways to perform magic. The exact nature of magic might very in interpretation: in some cases it is an energy or force, in others it is a science that is simply not understood (in the series Planetary it is referred to as a "cheat code for the world" in reference to video games where rules can be bent or broken with knowledge of the proper code). Even within the same universe, these rules may be interpreted in different ways, which is not to say that these are inconsistent, but rather that there may not necessarily be a single uniform form of magic.
In other cases, the character may be imbued with magical powers from an outside source, or perhaps gains a mystical artifact that augments their abilities. Captain Marvel (Billy Batson) is an example of this, who uses a magic word to transform himself into a superhuman with god-like powers.
Divinity is the quality of being a god or having been imbued with god-like power. Sometimes, an ancient god or goddess may give powers to a mere mortal, sometimes through an object, sometimes to the individual directly. Alternatively, the powered being may in fact BE a god or goddess, in which case the powers are their own. Those granted powers from deities may lose their powers if separated from the object of power said deity gave to them, or if the god ceases to bless them. Often there is overlap between magic and divinity, with heroes like Thor and Wonder Woman, who are divine, having magical objects or a deity (like Loki or Hera) who can use magical spells. It is also not uncommon for a divine entity to be tied to a mortal one, such as the Spectre often is or as Thor was in some of his earlier stories.
Technological Tools or Augmentation
There are many heroes who gain their powers from having technology being augmented to their bodies. In some cases, they are using tools that augment their natural abilities, often in the form of armor or rings. When this is the situation, the powers can be removed with the artifact that provides them, such is the case of Iron Man and Green Lantern. In many cases, the artifact might merge with the hero, such as with Jamie Reyes, who became the Blue Beetle, or might have artificial or mechanical elements placed inside of their bodies, such as Wolverine and Misty Knight. This might also include characters who are cyborgs, humans who have had considerable amounts of technology placed inside of their bodies or even robots, who are (often sentient) pieces of technology.
Physical Scientific Augmentation
A common form of power gain is through the body of the characters being altered scientifically, often on a genetic level. Some heroes are mutated by outside sources (as opposed to a natural mutation), such as Spider-Man, the Flash and the Fantastic Four being created by scientific accidents. In the early sixities, particularly in the Silver Age Marvel Comics, many accidental mutations or powers were linked to radiation such as the aforementioned Spider-Man and the Incredible Hulk.
Aliens from another planet whose powers are either normal on their planet or whose powers appeared due to the difference in the planets. Those that are born with their powers are much like mutants; they cannot lose them naturally, while the latter group may lose their powers when away from the planet that gives them power.
Some heroes and villains may be nothing more then average people who have undergone rigorous training to get at top human condition. They are but human, however, and therefore cannot achieve super speed, strength, or other powers. What they get usually
Some heroes and villains may never learn were their power came from and in some cases have elements that may or may not be powers. In some cases, it is discovered to be one of the above later on, and in some cases it is simply the case.
Notable Characters: Saitama
These are heroes who got their powers in a way not described above. The entire list of possibilities is endless.
Many ways of acquisition overlap. For example, someone's mutation may be the ability to cast magical spells. Perhaps, someone is given a mechanical wonder by a divine power. However, despite the ways heroes and villains receive their power, they all fall into a few simple categories.