In the ShowEdit
The planet was originally a thriving planet until war broke out between its two native nations, the Kaleds and the Thals. After 1000 years, the Kaleds mutated and were placed into Dalekanium travel suits by the scientist Davros. Davros then manipulated the Thals into firing a rocket at the un-mutated Kaled dome and then sent the mutants, now called Daleks, to 'Exterminate' all remaining Thals.
The war devastated much of Skaro's landscape, killing most life and causing lethal levels of radiation. The Daleks spread across the planet, "exterminating" any Thals they could find. However, the Doctor (in his first body/regeneration) arrived on the planet and convinced the Thals to fight the Daleks, taking over a city. Skaro was supposedly destroyed by the Hand of Omega in the episode Rememberance of the Daleks, however novels, comics and audio books say that the planet survived by either Daleks from the future placing a forcefield around the planet, protecting it from the Hand's destructive power or another planet was in orbit of where the planet was and was destroyed in it's place.
It is believed Skaro was officially destroyed in the Time War, as a member of the Cult of Skaro (a group of Daleks created by the Emperor to find new ways of keeping the race alive) stated "My planet is gone, destroyed in a Great War". The Dalek Asylum the Doctor visits in the episode 'Asylum of the Daleks' is NOT on Skaro, but it's on separate planet that survived the Last Great Time War until the planet was destroyed by the New Dalek Paradigm.
However, in the episode 'The Magician's Apprentice', it is revealed that Davros and a new group of Daleks managed to bring back Skaro, and had kept it invisible until the Doctor arrived.
In the ModEdit
Skaro Sand spawns on the surface of Skaro. Underground, Skaro Rock spawns in place of stone, and within it, veins of Dalekanium ore spawn. Skaro also has a large variety of Daleks spawn on the surface, including 60s, Special Weapon, Drones (red Daleks) and Eternals (yellow Daleks).
There are plans for new biomes on Skaro, including the Petrified Forest, Lake of Mutations and randomly spawning Dalek cities. Currently there are Crashed Dalek Ships that you can find randomly in the sides of mountains. They have decent treasure including Dalek parts, obsidian, nitro-9, and dalekanium.Long, long, ago, in the 1.5.2 version of the mod, Skaro was a biome that randomly spawned in the Overworld. The biome spawned with Skaro sand and had mountains of default stone. Skaro also had lakes of murky water, in which Marine Daleks spawned.