Digital Monsters, or Digimon, are creatures that hail from the Digital World (though they are able to exist in the human one as well). They come in many different forms, and at the moment there are over 800 species known at this time. There are different versions for how Digimon came into being, however, the common point is that they were created from data on somebody's computer, sometimes on purpose, sometimes accidentally.
Digimon have been known to partner with humans, on occasion. Upon doing so, the Digimon can grow immensely powerful! When the bond between the digimon and their partner grows deep enough, digivolution can take place! Some Digidestined are even able to Digivolve with their Digimon!
Digimon are similar to humans in many ways, though few digimon appear to be. They can be good, evil, or neutral. They can battle amongst themselves, though their attacks are rarely like those of a human. They can befriend other beings, or make enemies of them, depending on the digimon and upon whom they are interacting with.