The Digital World, often abbreviated as DigiWorld, is the homeworld of Digimon, aka Digital Monsters. Its various incarnations can usually be summed up as a cross between virtual reality and a parallel dimension to the Human world, as its existence is typically linked to the computers and internet of its corresponding Earth, generated in some way out of interpreting the mass amounts of data of computer and media networks into a physical, self-supporting representation. This is also why Digimon themselves have such a diverse range of forms, from resembling animals, machines or mythical beings to giving physical form to much more abstract concepts. It all depends on what data contributed to their generation.
The environment is equally and sometimes even moreso variable. Seeing a massive glacier next to a volcano and across from a desert residing near a tropical jungle in ways that would be impossible in the 'Real' world without destroying each other is not an uncommon sight, but can make travel extremely trying when not prepared for it. The landscape just doesn't always make sense, telephone poles and signposts with no purpose in middle of forests, mountains that are upside-down yet stable, and in some cases the corrupted of the world have been able to twist their domains in new and terrible ways to match their dark natures. In some versions the data-based nature is more evident, with cables, machinery and circuitry patterns intergrated visually into formations; in others the highly conflicting environmental proximities is the only clue.
Despite seeming to congergate in the same general vicinity of the Multiverse, the known instances of the DigiWorld have not fused directly together, the same metaphysical 'firewalls' if you will that keep them seperated from the human world keep them from overwriting each other as well. This may be a higher force's attempt at preventing each one's 'corrupted' aspects (Dark Gears, Nightmare Virus, ect) from trying to infect the other, though how long that may be successful is unknown. The bounderies also make travelling in or out of the DigiWorlds difficult, though finding access from the Multiverse in general is possible, it's extremely difficult. Depending on which version, one can either find, or in some artificially generate Digital Gates for the safest and most direct access.
Control of varies, and in some cases contested and fought over, between iterations. The Soverigns, the Devas, and the Royal Knights are just some of the known examples of guardian or enforcer castes. In some versions, the computer-like Yydrassil is regarded as a god-like entity amongst Digimon.
At least three known iterations of the DigiWorld are currently know, referred loosely to by which generation of human/digimon partners protects it: Chosen (Adventure and 02), Tamers (Digimon Tamers), and Savers (Digmon Savers and Virus Busters).